{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2025-39673", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-04-16T07:20:57.112Z", "datePublished": "2025-09-05T17:20:38.769Z", "dateUpdated": "2026-08-05T12:04:28.071Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:04:28.071Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nppp: fix race conditions in ppp_fill_forward_path\n\nppp_fill_forward_path() has two race conditions:\n\n1. The ppp->channels list can change between list_empty() and\n list_first_entry(), as ppp_lock() is not held. If the only channel\n is deleted in ppp_disconnect_channel(), list_first_entry() may\n access an empty head or a freed entry, and trigger a panic.\n\n2. pch->chan can be NULL. When ppp_unregister_channel() is called,\n pch->chan is set to NULL before pch is removed from ppp->channels.\n\nFix these by using a lockless RCU approach:\n- Use list_first_or_null_rcu() to safely test and access the first list\n entry.\n- Convert list modifications on ppp->channels to their RCU variants and\n add synchronize_net() after removal.\n- Check for a NULL pch->chan before dereferencing it." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL" }, "scenarios": [ { "lang": "en", "value": "AV:N - The race's teardown side is reachable from received packets — an unauthenticated spoofed PPPoE PADT frame drives `pppoe_disc_rcv()` → `ppp_unregister_channel()`, and remote L2TP/PPTP peers drive the same teardown over routed IP — while the reader side is triggered by ordinary forwarded traffic entering the nftables flowtable/HW-offload path from any remote host.\nAC:L - The attacker controls both sides of the race and can retry indefinitely: repeated session teardowns concurrently with a stream of new forwarded connections that each invoke `ppp_fill_forward_path()`, on a widely deployed default configuration (PPPoE/L2TP WAN plus flow offload).\nPR:N - PADT injection requires no credentials whatsoever (`pppoe_disc_rcv()` matches only session-id and source MAC, both observable), and generating forwarded traffic requires none; even the local variant only needs CAP_NET_ADMIN, which is obtainable unprivileged via user namespaces.\nUI:N - No victim action is needed — the attacker supplies both the teardown trigger and the forwarded traffic; PPP session teardown on remote protocol messages is automatic daemon behaviour, not user interaction.\nS:U - The corruption and its consequences are confined to the kernel's own security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - The commit states `list_first_entry()` may return \"a freed entry\", giving a use-after-free read of a `struct channel` slab object, and the empty-head case yields an unbounded wild-pointer read through `chan->ops`, both usable to disclose arbitrary kernel memory.\nI:H - The UAF terminates in an indirect call through `chan->ops->fill_forward_path`, so an attacker who reclaims the freed `struct channel` allocation with sprayed data controls the function pointer, yielding control-flow hijack rather than a mere read.\nA:H - The commit explicitly says the list race will \"trigger a panic\", and the second race is an outright NULL dereference on `chan->ops` — either way a remotely reproducible kernel oops on a router in the forwarding fast path." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/net/ppp/ppp_generic.c" ], "versions": [ { "version": "f6efc675c9dd8d93f826b79ae7e33e03301db609", "lessThan": "9a1969fbffc1f1900d92d7594b1b7d8d72ef3dc7", "status": "affected", "versionType": "git" }, { "version": "f6efc675c9dd8d93f826b79ae7e33e03301db609", "lessThan": "0f1630be6fcca3f0c63e4b242ad202e5cde28a40", "status": "affected", "versionType": "git" }, { "version": "f6efc675c9dd8d93f826b79ae7e33e03301db609", "lessThan": "ca18d751bcc9faf5b7e82e9fae1223d103928181", "status": "affected", "versionType": "git" }, { "version": "f6efc675c9dd8d93f826b79ae7e33e03301db609", "lessThan": "94731cc551e29511d85aa8dec61a6c071b1f2430", "status": "affected", "versionType": "git" }, { "version": "f6efc675c9dd8d93f826b79ae7e33e03301db609", "lessThan": "f97f6475fdcb3c28ff3c55cc4b7bde632119ec08", "status": "affected", "versionType": "git" }, { "version": "f6efc675c9dd8d93f826b79ae7e33e03301db609", "lessThan": "0417adf367a0af11adf7ace849af4638cfb573f7", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/net/ppp/ppp_generic.c" ], "versions": [ { "version": "5.13", "status": "affected" }, { "version": "0", "lessThan": "5.13", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.190", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.149", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.103", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.44", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.16.4", "lessThanOrEqual": "6.16.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.17", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.13", "versionEndExcluding": "5.15.190" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.13", "versionEndExcluding": "6.1.149" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.13", "versionEndExcluding": "6.6.103" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.13", "versionEndExcluding": "6.12.44" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.13", "versionEndExcluding": "6.16.4" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.13", "versionEndExcluding": "6.17" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/9a1969fbffc1f1900d92d7594b1b7d8d72ef3dc7" }, { "url": "https://git.kernel.org/stable/c/0f1630be6fcca3f0c63e4b242ad202e5cde28a40" }, { "url": "https://git.kernel.org/stable/c/ca18d751bcc9faf5b7e82e9fae1223d103928181" }, { "url": "https://git.kernel.org/stable/c/94731cc551e29511d85aa8dec61a6c071b1f2430" }, { "url": "https://git.kernel.org/stable/c/f97f6475fdcb3c28ff3c55cc4b7bde632119ec08" }, { "url": "https://git.kernel.org/stable/c/0417adf367a0af11adf7ace849af4638cfb573f7" } ], "title": "ppp: fix race conditions in ppp_fill_forward_path", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "title": "CVE Program Container", "references": [ { "url": "https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html" } ], "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2025-11-03T17:42:08.016Z" } }, { "x_adpType": "supplier", "providerMetadata": { "orgId": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e", "shortName": "siemens-SADP", "dateUpdated": "2026-05-12T12:06:04.160Z" }, "affected": [ { "vendor": "Siemens", "product": "SIMATIC CN 4100", "versions": [ { "status": "affected", "version": "0", "lessThan": "V5.0", "versionType": "custom" } ], "defaultStatus": "unknown" } ], "references": [ { "url": "https://cert-portal.siemens.com/productcert/html/ssa-032379.html" } ] } ] } }