{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-104635", "assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "state": "PUBLISHED", "assignerShortName": "EEF", "dateReserved": "2026-10-08T14:45:01.406Z", "datePublished": "2026-10-09T08:17:52.372Z", "dateUpdated": "2026-10-15T15:57:11.974Z" }, "containers": { "cna": { "affected": [ { "collectionURL": "https://repo.hex.pm", "cpes": [ "cpe:2.3:a:elixir-protobuf:protobuf:*:*:*:*:*:*:*:*" ], "defaultStatus": "unaffected", "modules": [ "'Elixir.Protobuf.JSON.Decode'", "'Elixir.Protobuf.JSON'" ], "packageName": "protobuf", "packageURL": "pkg:hex/protobuf", "product": "protobuf", "programFiles": [ "lib/protobuf/json/decode.ex", "lib/protobuf/json.ex" ], "programRoutines": [ { "name": "'Elixir.Protobuf.JSON.Decode':from_json_data/3" }, { "name": "'Elixir.Protobuf.JSON.Decode':decode_singular/3" }, { "name": "'Elixir.Protobuf.JSON':decode/3" }, { "name": "'Elixir.Protobuf.JSON':decode!/3" }, { "name": "'Elixir.Protobuf.JSON':from_decoded/3" } ], "repo": "https://github.com/elixir-protobuf/protobuf", "vendor": "elixir-protobuf", "versions": [ { "lessThan": "0.17.1", "status": "affected", "version": "0.8.0", "versionType": "semver" } ] }, { "collectionURL": "https://github.com", "cpes": [ "cpe:2.3:a:elixir-protobuf:protobuf:*:*:*:*:*:*:*:*" ], "defaultStatus": "unaffected", "modules": [ "'Elixir.Protobuf.JSON.Decode'", "'Elixir.Protobuf.JSON'" ], "packageName": "elixir-protobuf/protobuf", "packageURL": "pkg:github/elixir-protobuf/protobuf", "product": "protobuf", "programFiles": [ "lib/protobuf/json/decode.ex", "lib/protobuf/json.ex" ], "programRoutines": [ { "name": "'Elixir.Protobuf.JSON.Decode':from_json_data/3" }, { "name": "'Elixir.Protobuf.JSON.Decode':decode_singular/3" }, { "name": "'Elixir.Protobuf.JSON':decode/3" }, { "name": "'Elixir.Protobuf.JSON':decode!/3" }, { "name": "'Elixir.Protobuf.JSON':from_decoded/3" } ], "repo": "https://github.com/elixir-protobuf/protobuf", "vendor": "elixir-protobuf", "versions": [ { "lessThan": "e9432ad1c4099511905353cebcececa3a1f7c3ff", "status": "affected", "version": "b0a1d4eaffaf50012fa71a8e931a47cf252d0370", "versionType": "git" } ] } ], "configurations": [ { "lang": "en", "supportingMedia": [ { "base64": false, "type": "text/html", "value": "

The application decodes attacker-controlled JSON with Protobuf.JSON.decode/3, Protobuf.JSON.decode!/3, or Protobuf.JSON.from_decoded/3 into a message type whose schema contains a self-referential or cyclic embedded message.

" }, { "base64": false, "type": "text/markdown", "value": "The application decodes attacker-controlled JSON with `Protobuf.JSON.decode/3`, `Protobuf.JSON.decode!/3`, or `Protobuf.JSON.from_decoded/3` into a message type whose schema contains a self-referential or cyclic embedded message." } ], "value": "The application decodes attacker-controlled JSON with Protobuf.JSON.decode/3, Protobuf.JSON.decode!/3, or Protobuf.JSON.from_decoded/3 into a message type whose schema contains a self-referential or cyclic embedded message." } ], "cpeApplicability": [ { "nodes": [ { "cpeMatch": [ { "criteria": "cpe:2.3:a:elixir-protobuf:protobuf:*:*:*:*:*:*:*:*", "versionEndExcluding": "0.17.1", "versionStartIncluding": "0.8.0", "vulnerable": true } ], "negate": false, "operator": "OR" } ], "operator": "AND" } ], "credits": [ { "lang": "en", "type": "reporter", "value": "Daniel Coles" }, { "lang": "en", "type": "finder", "value": "Daniel Coles" }, { "lang": "en", "type": "remediation developer", "value": "Andrea Leopardi" }, { "lang": "en", "type": "coordinator", "value": "Jonatan Männchen / EEF" } ], "dateAssigned": "2026-10-08T15:40:42.000Z", "datePublic": "2026-10-09T08:17:52.000Z", "descriptions": [ { "lang": "en", "supportingMedia": [ { "base64": false, "type": "text/html", "value": "

Uncontrolled Recursion vulnerability in Protobuf.JSON.Decode in elixir-protobuf protobuf allows an unauthenticated remote attacker to crash the decoding process via a deeply nested JSON document. Any application that decodes attacker-supplied JSON with Protobuf.JSON.decode/3, Protobuf.JSON.decode!/3, or Protobuf.JSON.from_decoded/3 into a schema that contains a self-referential or cyclic message type is affected.

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In lib/protobuf/json/decode.ex, the embedded-message clause of decode_singular/3 recurses into internal_from_json_data/3 once per nesting level without incrementing or checking the decoder's depth counter. The depth guard increase_depth_and_maybe_throw/1 covers only the Google.Protobuf.ListValue and Google.Protobuf.Struct clauses, so the recursion_limit option has no effect on user-defined message types. Each nesting level allocates a stack frame and heap objects, and a sufficiently deep document exhausts the memory of the decoding process. Confidentiality and integrity are not affected.

\n

This issue affects protobuf: from 0.8.0 before 0.17.1.

" }, { "base64": false, "type": "text/markdown", "value": "Uncontrolled Recursion vulnerability in `Protobuf.JSON.Decode` in elixir-protobuf protobuf allows an unauthenticated remote attacker to crash the decoding process via a deeply nested JSON document. Any application that decodes attacker-supplied JSON with `Protobuf.JSON.decode/3`, `Protobuf.JSON.decode!/3`, or `Protobuf.JSON.from_decoded/3` into a schema that contains a self-referential or cyclic message type is affected.\n\nIn `lib/protobuf/json/decode.ex`, the embedded-message clause of `decode_singular/3` recurses into `internal_from_json_data/3` once per nesting level without incrementing or checking the decoder's depth counter. The depth guard `increase_depth_and_maybe_throw/1` covers only the `Google.Protobuf.ListValue` and `Google.Protobuf.Struct` clauses, so the `recursion_limit` option has no effect on user-defined message types. Each nesting level allocates a stack frame and heap objects, and a sufficiently deep document exhausts the memory of the decoding process. Confidentiality and integrity are not affected.\n\nThis issue affects protobuf: from 0.8.0 before 0.17.1." } ], "value": "Uncontrolled Recursion vulnerability in Protobuf.JSON.Decode in elixir-protobuf protobuf allows an unauthenticated remote attacker to crash the decoding process via a deeply nested JSON document. Any application that decodes attacker-supplied JSON with Protobuf.JSON.decode/3, Protobuf.JSON.decode!/3, or Protobuf.JSON.from_decoded/3 into a schema that contains a self-referential or cyclic message type is affected.\n\nIn lib/protobuf/json/decode.ex, the embedded-message clause of decode_singular/3 recurses into internal_from_json_data/3 once per nesting level without incrementing or checking the decoder's depth counter. The depth guard increase_depth_and_maybe_throw/1 covers only the Google.Protobuf.ListValue and Google.Protobuf.Struct clauses, so the recursion_limit option has no effect on user-defined message types. Each nesting level allocates a stack frame and heap objects, and a sufficiently deep document exhausts the memory of the decoding process. Confidentiality and integrity are not affected.\n\nThis issue affects protobuf: from 0.8.0 before 0.17.1." } ], "impacts": [ { "capecId": "CAPEC-230", "descriptions": [ { "lang": "en", "supportingMedia": [ { "base64": false, "type": "text/html", "value": "

An unauthenticated client that can reach an endpoint decoding JSON into a self-referential message type can crash the decoding process through stack and memory exhaustion with a single request. Repeated or concurrent requests can exhaust the memory of the whole node and disrupt co-located workloads.

" }, { "base64": false, "type": "text/markdown", "value": "An unauthenticated client that can reach an endpoint decoding JSON into a self-referential message type can crash the decoding process through stack and memory exhaustion with a single request. Repeated or concurrent requests can exhaust the memory of the whole node and disrupt co-located workloads." } ], "value": "An unauthenticated client that can reach an endpoint decoding JSON into a self-referential message type can crash the decoding process through stack and memory exhaustion with a single request. Repeated or concurrent requests can exhaust the memory of the whole node and disrupt co-located workloads." } ] } ], "metrics": [ { "cvssV4_0": { "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "attackVector": "NETWORK", "baseScore": 8.2, "baseSeverity": "HIGH", "privilegesRequired": "NONE", "providerUrgency": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "userInteraction": "NONE", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N", "version": "4.0", "vulnAvailabilityImpact": "HIGH", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "vulnerabilityResponseEffort": "NOT_DEFINED" }, "format": "CVSS", "scenarios": [ { "lang": "en", "value": "GENERAL" } ] } ], "problemTypes": [ { "descriptions": [ { "cweId": "CWE-674", "description": "CWE-674 Uncontrolled Recursion", "lang": "en", "type": "CWE" } ] } ], "providerMetadata": { "orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "shortName": "EEF", "dateUpdated": "2026-10-09T09:24:37.025Z" }, "references": [ { "name": "GitHub Advisory", "tags": [ "related", "vendor-advisory" ], "url": "https://github.com/elixir-protobuf/protobuf/security/advisories/GHSA-m497-c2h9-rvw6" }, { "name": "EEF CNA record for CVE-2026-104635", "tags": [ "related" ], "url": "https://cna.erlef.org/cves/CVE-2026-104635.html" }, { "name": "OSV record EEF-CVE-2026-104635", "tags": [ "related" ], "url": "https://osv.dev/vulnerability/EEF-CVE-2026-104635" }, { "name": "Introducing commit b0a1d4e in elixir-protobuf/protobuf", "tags": [ "related" ], "url": "https://github.com/elixir-protobuf/protobuf/commit/b0a1d4eaffaf50012fa71a8e931a47cf252d0370" }, { "name": "Fix commit e9432ad in elixir-protobuf/protobuf", "tags": [ "patch" ], "url": "https://github.com/elixir-protobuf/protobuf/commit/e9432ad1c4099511905353cebcececa3a1f7c3ff" } ], "source": { "discovery": "EXTERNAL" }, "title": "Uncontrolled recursion in elixir-protobuf/protobuf JSON decoding of self-referential messages", "workarounds": [ { "lang": "en", "supportingMedia": [ { "base64": false, "type": "text/html", "value": "

Reject JSON documents whose nesting depth exceeds a fixed bound at the web or middleware layer before passing them to the decoder. No decoder option limits recursion for user-defined message types, so the check must happen before Protobuf.JSON.decode/3, Protobuf.JSON.decode!/3, or Protobuf.JSON.from_decoded/3 is called.

" }, { "base64": false, "type": "text/markdown", "value": "Reject JSON documents whose nesting depth exceeds a fixed bound at the web or middleware layer before passing them to the decoder. No decoder option limits recursion for user-defined message types, so the check must happen before `Protobuf.JSON.decode/3`, `Protobuf.JSON.decode!/3`, or `Protobuf.JSON.from_decoded/3` is called." } ], "value": "Reject JSON documents whose nesting depth exceeds a fixed bound at the web or middleware layer before passing them to the decoder. No decoder option limits recursion for user-defined message types, so the check must happen before Protobuf.JSON.decode/3, Protobuf.JSON.decode!/3, or Protobuf.JSON.from_decoded/3 is called." } ], "x_proofOfConcept": [ { "lang": "en", "supportingMedia": [ { "base64": false, "type": "text/html", "value": "
    \n
  1. Define and compile a self-referential proto3 message, for example a TreeNode message with a single embedded field child of type TreeNode.
    2. \n
  2. Build a JSON document that nests the child field several thousand levels deep, for example by wrapping {} in {\"child\": ...} 5,000 times.
    3. \n
  3. Decode it with Protobuf.JSON.decode(json, TreeNode, recursion_limit: 100).
    4. \n
  4. Observe that no Protobuf.JSON.DecodeError for an exceeded recursion limit is raised and the decoder walks every level. The same depth in a Google.Protobuf.Struct payload raises {:recursion_limit_exceeded, 100}. At larger depths the decoding process consumes hundreds of megabytes and crashes with stack and heap exhaustion.
    5. \n
" }, { "base64": false, "type": "text/markdown", "value": "1. Define and compile a self-referential proto3 message, for example a `TreeNode` message with a single embedded field `child` of type `TreeNode`.\n2. Build a JSON document that nests the `child` field several thousand levels deep, for example by wrapping `{}` in `{\"child\": ...}` 5,000 times.\n3. Decode it with `Protobuf.JSON.decode(json, TreeNode, recursion_limit: 100)`.\n4. Observe that no `Protobuf.JSON.DecodeError` for an exceeded recursion limit is raised and the decoder walks every level. The same depth in a `Google.Protobuf.Struct` payload raises `{:recursion_limit_exceeded, 100}`. At larger depths the decoding process consumes hundreds of megabytes and crashes with stack and heap exhaustion." } ], "value": "* Define and compile a self-referential proto3 message, for example a TreeNode message with a single embedded field child of type TreeNode.\n* Build a JSON document that nests the child field several thousand levels deep, for example by wrapping {} in {\"child\": ...} 5,000 times.\n* Decode it with Protobuf.JSON.decode(json, TreeNode, recursion_limit: 100).\n* Observe that no Protobuf.JSON.DecodeError for an exceeded recursion limit is raised and the decoder walks every level. The same depth in a Google.Protobuf.Struct payload raises {:recursion_limit_exceeded, 100}. At larger depths the decoding process consumes hundreds of megabytes and crashes with stack and heap exhaustion." } ], "x_technicalAnalysis": [ { "lang": "en", "supportingMedia": [ { "base64": false, "type": "text/html", "value": "

1. Entry points. Protobuf.JSON.decode/3, Protobuf.JSON.decode!/3, and Protobuf.JSON.from_decoded/3 in lib/protobuf/json.ex validate options and call Protobuf.JSON.Decode.from_json_data/3, which builds a state map carrying depth: 0 and the recursion_limit (default 100). from_decoded/3 accepts already-parsed data, so the underlying JSON parser never bounds the depth either.

\n

2. Unguarded recursion. For a user-defined message module, internal_from_json_data/3 calls decode_message/4, which calls decode_regular_fields/3 and decode_oneof_fields/3. Each field value passes through decode_value/3 and, for a singular embedded message, reaches the decode_singular/3 clause matching embedded?: true. That clause calls internal_from_json_data/3 with state unchanged, so state.depth stays at 0 at every nesting level. Repeated fields and map values reach the same clause through decode_repeated/3 and decode_map/3.

\n

3. Guard coverage. increase_depth_and_maybe_throw/1 increments depth and throws {:recursion_limit_exceeded, limit} when it exceeds the limit. It is called only from the Google.Protobuf.ListValue and Google.Protobuf.Struct clauses, which the Google.Protobuf.Value clause delegates to. The recursion_limit documentation scopes the option to those wrappers, and no other path checks depth.

\n

4. Result. A self-referential schema such as a Tree message with a Tree child field recurses once per JSON nesting level with no bound. Each level holds a live stack frame and allocates heap objects, so a sufficiently deep document exhausts the memory of the decoding process and crashes it. The BEAM max_heap_size process flag defaults to unlimited, so repeated or concurrent requests can exhaust the memory of the whole node.

" }, { "base64": false, "type": "text/markdown", "value": "**1. Entry points.** `Protobuf.JSON.decode/3`, `Protobuf.JSON.decode!/3`, and `Protobuf.JSON.from_decoded/3` in `lib/protobuf/json.ex` validate options and call `Protobuf.JSON.Decode.from_json_data/3`, which builds a `state` map carrying `depth: 0` and the `recursion_limit` (default 100). `from_decoded/3` accepts already-parsed data, so the underlying JSON parser never bounds the depth either.\n\n**2. Unguarded recursion.** For a user-defined message module, `internal_from_json_data/3` calls `decode_message/4`, which calls `decode_regular_fields/3` and `decode_oneof_fields/3`. Each field value passes through `decode_value/3` and, for a singular embedded message, reaches the `decode_singular/3` clause matching `embedded?: true`. That clause calls `internal_from_json_data/3` with `state` unchanged, so `state.depth` stays at 0 at every nesting level. Repeated fields and map values reach the same clause through `decode_repeated/3` and `decode_map/3`.\n\n**3. Guard coverage.** `increase_depth_and_maybe_throw/1` increments `depth` and throws `{:recursion_limit_exceeded, limit}` when it exceeds the limit. It is called only from the `Google.Protobuf.ListValue` and `Google.Protobuf.Struct` clauses, which the `Google.Protobuf.Value` clause delegates to. The `recursion_limit` documentation scopes the option to those wrappers, and no other path checks depth.\n\n**4. Result.** A self-referential schema such as a `Tree` message with a `Tree child` field recurses once per JSON nesting level with no bound. Each level holds a live stack frame and allocates heap objects, so a sufficiently deep document exhausts the memory of the decoding process and crashes it. The BEAM `max_heap_size` process flag defaults to unlimited, so repeated or concurrent requests can exhaust the memory of the whole node." } ], "value": "1. Entry points. Protobuf.JSON.decode/3, Protobuf.JSON.decode!/3, and Protobuf.JSON.from_decoded/3 in lib/protobuf/json.ex validate options and call Protobuf.JSON.Decode.from_json_data/3, which builds a state map carrying depth: 0 and the recursion_limit (default 100). from_decoded/3 accepts already-parsed data, so the underlying JSON parser never bounds the depth either.\n\n2. Unguarded recursion. For a user-defined message module, internal_from_json_data/3 calls decode_message/4, which calls decode_regular_fields/3 and decode_oneof_fields/3. Each field value passes through decode_value/3 and, for a singular embedded message, reaches the decode_singular/3 clause matching embedded?: true. That clause calls internal_from_json_data/3 with state unchanged, so state.depth stays at 0 at every nesting level. Repeated fields and map values reach the same clause through decode_repeated/3 and decode_map/3.\n\n3. Guard coverage. increase_depth_and_maybe_throw/1 increments depth and throws {:recursion_limit_exceeded, limit} when it exceeds the limit. It is called only from the Google.Protobuf.ListValue and Google.Protobuf.Struct clauses, which the Google.Protobuf.Value clause delegates to. The recursion_limit documentation scopes the option to those wrappers, and no other path checks depth.\n\n4. Result. A self-referential schema such as a Tree message with a Tree child field recurses once per JSON nesting level with no bound. Each level holds a live stack frame and allocates heap objects, so a sufficiently deep document exhausts the memory of the decoding process and crashes it. The BEAM max_heap_size process flag defaults to unlimited, so repeated or concurrent requests can exhaust the memory of the whole node." } ] }, "adp": [ { "references": [ { "url": "https://osv.dev/vulnerability/EEF-CVE-2026-104635", "tags": [ "exploit" ] } ], "metrics": [ { "other": { "type": "ssvc", "content": { "timestamp": "2026-10-15T15:56:39.227631Z", "id": "CVE-2026-104635", "options": [ { "Exploitation": "poc" }, { "Automatable": "no" }, { "Technical Impact": "partial" } ], "role": "CISA Coordinator", "version": "2.0.3" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-15T15:57:11.974Z" } } ] } }