{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2021-47131", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-03-04T18:12:48.840Z", "datePublished": "2024-03-15T20:14:34.647Z", "dateUpdated": "2026-08-05T08:46:13.224Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T08:46:13.224Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/tls: Fix use-after-free after the TLS device goes down and up\n\nWhen a netdev with active TLS offload goes down, tls_device_down is\ncalled to stop the offload and tear down the TLS context. However, the\nsocket stays alive, and it still points to the TLS context, which is now\ndeallocated. If a netdev goes up, while the connection is still active,\nand the data flow resumes after a number of TCP retransmissions, it will\nlead to a use-after-free of the TLS context.\n\nThis commit addresses this bug by keeping the context alive until its\nnormal destruction, and implements the necessary fallbacks, so that the\nconnection can resume in software (non-offloaded) kTLS mode.\n\nOn the TX side tls_sw_fallback is used to encrypt all packets. The RX\nside already has all the necessary fallbacks, because receiving\nnon-decrypted packets is supported. The thing needed on the RX side is\nto block resync requests, which are normally produced after receiving\nnon-decrypted packets.\n\nThe necessary synchronization is implemented for a graceful teardown:\nfirst the fallbacks are deployed, then the driver resources are released\n(it used to be possible to have a tls_dev_resync after tls_dev_del).\n\nA new flag called TLS_RX_DEV_DEGRADED is added to indicate the fallback\nmode. It's used to skip the RX resync logic completely, as it becomes\nuseless, and some objects may be released (for example, resync_async,\nwhich is allocated and freed by the driver)." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 8.1, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:N - The UAF is reached when a remote TLS peer sends data on an existing kTLS hardware-offloaded TCP connection after the NIC flaps, hitting net/tls RX resync paths that dereference driver state freed by tls_dev_del.\nAC:H - Exploitation requires the offload netdev to go down and back up while the connection stays alive, which a remote peer cannot force; once that state exists, sending traffic reliably triggers the bug.\nPR:N - A remote TLS client or peer needs no local account or privileges—only an established connection to a host using kTLS device offload (for example HTTPS with NIC TLS offload).\nUI:N - No additional user action is required beyond ordinary connection and data transfer after the device cycle; the attacker does not need a victim to open a file or click anything.\nS:U - Impact is confined to the host kernel that owns the TLS offload context; this is standard kernel memory corruption without a VM/IOMMU or other security-authority boundary cross.\nC:H - Use-after-free of the driver RX resync object (and related offload state) enables heap reuse and arbitrary read primitives per UAF scoring guidance.\nI:H - The same UAF is exploitable for heap spray and control-flow hijacking/arbitrary write, and the missing TX fallback can also mishandle post-teardown xmit state.\nA:H - Dereferencing freed resync_async or calling tls_dev_resync after tls_dev_del can oops/panic the kernel, so availability impact is High." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "include/net/tls.h", "net/tls/tls_device.c", "net/tls/tls_device_fallback.c", "net/tls/tls_main.c" ], "versions": [ { "version": "e8f69799810c32dd40c6724d829eccc70baad07f", "lessThan": "f1d4184f128dede82a59a841658ed40d4e6d3aa2", "status": "affected", "versionType": "git" }, { "version": "e8f69799810c32dd40c6724d829eccc70baad07f", "lessThan": "0f1e6fe66977a864fe850522316f713d7b926fd9", "status": "affected", "versionType": "git" }, { "version": "e8f69799810c32dd40c6724d829eccc70baad07f", "lessThan": "c55dcdd435aa6c6ad6ccac0a4c636d010ee367a4", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "include/net/tls.h", "net/tls/tls_device.c", "net/tls/tls_device_fallback.c", "net/tls/tls_main.c" ], "versions": [ { "version": "4.18", "status": "affected" }, { "version": "0", "lessThan": "4.18", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.43", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.12.10", "lessThanOrEqual": "5.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.13", "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": "4.18", "versionEndExcluding": "5.10.43" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.18", "versionEndExcluding": "5.12.10" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.18", "versionEndExcluding": "5.13" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/f1d4184f128dede82a59a841658ed40d4e6d3aa2" }, { "url": "https://git.kernel.org/stable/c/0f1e6fe66977a864fe850522316f713d7b926fd9" }, { "url": "https://git.kernel.org/stable/c/c55dcdd435aa6c6ad6ccac0a4c636d010ee367a4" } ], "title": "net/tls: Fix use-after-free after the TLS device goes down and up", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "title": "CISA ADP Vulnrichment", "metrics": [ { "other": { "type": "ssvc", "content": { "id": "CVE-2021-47131", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "partial" } ], "version": "2.0.3", "timestamp": "2024-03-19T15:23:46.487605Z" } } } ], "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2024-06-04T17:14:12.171Z" } }, { "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2024-08-04T05:24:39.881Z" }, "title": "CVE Program Container", "references": [ { "url": "https://git.kernel.org/stable/c/f1d4184f128dede82a59a841658ed40d4e6d3aa2", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/0f1e6fe66977a864fe850522316f713d7b926fd9", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/c55dcdd435aa6c6ad6ccac0a4c636d010ee367a4", "tags": [ "x_transferred" ] } ] } ] } }