{"id":"CVE-2026-31533","state":"PUBLISHED","title":"net/tls: fix use-after-free in -EBUSY error path of tls_do_encryption","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/tls: fix use-after-free in -EBUSY error path of tls_do_encryption\n\nThe -EBUSY handling in tls_do_encryption(), introduced by commit\n859054147318 (\"net: tls: handle backlogging of crypto requests\"), has\na use-after-free due to double cleanup of encrypt_pending and the\nscatterlist entry.\n\nWhen crypto_aead_encrypt() returns -EBUSY, the request is enqueued to\nthe cryptd backlog and the async callback tls_encrypt_done() will be\ninvoked upon completion. That callback unconditionally restores the\nscatterlist entry (sge->offset, sge->length) and decrements\nctx->encrypt_pending. However, if tls_encrypt_async_wait() returns an\nerror, the synchronous error path in tls_do_encryption() performs the\nsame cleanup again, double-decrementing encrypt_pending and\ndouble-restoring the scatterlist.\n\nThe double-decrement corrupts the encrypt_pending sentinel (initialized\nto 1), making tls_encrypt_async_wait() permanently skip the wait for\npending async callbacks. A subsequent sendmsg can then free the\ntls_rec via bpf_exec_tx_verdict() while a cryptd callback is still\npending, resulting in a use-after-free when the callback fires on the\nfreed record.\n\nFix this by skipping the synchronous cleanup when the -EBUSY async\nwait returns an error, since the callback has already handled\nencrypt_pending and sge restoration.","publishedAt":"2026-04-23T15:11:06.955Z","updatedAt":"2026-10-19T18:45:55.376Z","severity":{"score":9.8,"label":"Critical","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"3ade391adc584f17b5570fd205de3ad029090368","status":"affected","lessThan":"414fc5e5a5aff776c150f1b86770e0a25a35df3a","versionType":"git"},{"version":"cd1bbca03f3c1d845ce274c0d0a66de8e5929f72","status":"affected","lessThan":"02f3ecadb23558bbe068e6504118f1b712d4ece0","versionType":"git"},{"version":"13eca403876bbea3716e82cdfe6f1e6febb38754","status":"affected","lessThan":"0e43e0a3c94044acc74b8e0927c27972eb5a59e8","versionType":"git"},{"version":"8590541473188741055d27b955db0777569438e3","status":"affected","lessThan":"aa9facde6c5005205874c37db3fd25799d741baf","versionType":"git"},{"version":"8590541473188741055d27b955db0777569438e3","status":"affected","lessThan":"5d70eb25b41e9b010828cd12818b06a0c3b04412","versionType":"git"},{"version":"8590541473188741055d27b955db0777569438e3","status":"affected","lessThan":"2694d408b0e595024e0fc1d64ff9db0358580f74","versionType":"git"},{"version":"8590541473188741055d27b955db0777569438e3","status":"affected","lessThan":"a9b8b18364fffce4c451e6f6fd218fa4ab646705","versionType":"git"},{"version":"ab6397f072e5097f267abf5cb08a8004e6b17694","status":"affected","versionType":"git"},{"version":"5.15.160","status":"affected","lessThan":"5.15.203","versionType":"semver"},{"version":"6.1.84","status":"affected","lessThan":"6.1.169","versionType":"semver"},{"version":"6.6.18","status":"affected","lessThan":"6.6.135","versionType":"semver"},{"version":"6.7.6","status":"affected","lessThan":"6.8","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/tls/tls_sw.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.8","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.8","versionType":"semver"},{"version":"5.15.203","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.169","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.135","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.82","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.23","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.13","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/tls/tls_sw.c"]}],"references":["https://git.kernel.org/stable/c/414fc5e5a5aff776c150f1b86770e0a25a35df3a","https://git.kernel.org/stable/c/02f3ecadb23558bbe068e6504118f1b712d4ece0","https://git.kernel.org/stable/c/0e43e0a3c94044acc74b8e0927c27972eb5a59e8","https://git.kernel.org/stable/c/aa9facde6c5005205874c37db3fd25799d741baf","https://git.kernel.org/stable/c/5d70eb25b41e9b010828cd12818b06a0c3b04412","https://git.kernel.org/stable/c/2694d408b0e595024e0fc1d64ff9db0358580f74","https://git.kernel.org/stable/c/a9b8b18364fffce4c451e6f6fd218fa4ab646705","https://cert-portal.siemens.com/productcert/html/ssa-082556.html","https://cert-portal.siemens.com/productcert/html/ssa-019113.html","https://cert-portal.siemens.com/productcert/html/ssa-457936.html"],"weaknesses":["CWE-416"],"ingestedAt":"2026-10-29T20:11:40.391Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/31xxx/CVE-2026-31533.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-31533","state":"PUBLISHED","datePublished":"2026-04-23T15:11:06.955Z","dateUpdated":"2026-10-19T18:45:55.376Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-03-09T15:48:24.113Z"},"containers":{"cna":{"title":"net/tls: fix use-after-free in -EBUSY error path of tls_do_encryption","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/tls: fix use-after-free in -EBUSY error path of tls_do_encryption\n\nThe -EBUSY handling in tls_do_encryption(), introduced by commit\n859054147318 (\"net: tls: handle backlogging of crypto requests\"), has\na use-after-free due to double cleanup of encrypt_pending and the\nscatterlist entry.\n\nWhen crypto_aead_encrypt() returns -EBUSY, the request is enqueued to\nthe cryptd backlog and the async callback tls_encrypt_done() will be\ninvoked upon completion. That callback unconditionally restores the\nscatterlist entry (sge->offset, sge->length) and decrements\nctx->encrypt_pending. However, if tls_encrypt_async_wait() returns an\nerror, the synchronous error path in tls_do_encryption() performs the\nsame cleanup again, double-decrementing encrypt_pending and\ndouble-restoring the scatterlist.\n\nThe double-decrement corrupts the encrypt_pending sentinel (initialized\nto 1), making tls_encrypt_async_wait() permanently skip the wait for\npending async callbacks. A subsequent sendmsg can then free the\ntls_rec via bpf_exec_tx_verdict() while a cryptd callback is still\npending, resulting in a use-after-free when the callback fires on the\nfreed record.\n\nFix this by skipping the synchronous cleanup when the -EBUSY async\nwait returns an error, since the callback has already handled\nencrypt_pending and sge restoration."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"3ade391adc584f17b5570fd205de3ad029090368","status":"affected","lessThan":"414fc5e5a5aff776c150f1b86770e0a25a35df3a","versionType":"git"},{"version":"cd1bbca03f3c1d845ce274c0d0a66de8e5929f72","status":"affected","lessThan":"02f3ecadb23558bbe068e6504118f1b712d4ece0","versionType":"git"},{"version":"13eca403876bbea3716e82cdfe6f1e6febb38754","status":"affected","lessThan":"0e43e0a3c94044acc74b8e0927c27972eb5a59e8","versionType":"git"},{"version":"8590541473188741055d27b955db0777569438e3","status":"affected","lessThan":"aa9facde6c5005205874c37db3fd25799d741baf","versionType":"git"},{"version":"8590541473188741055d27b955db0777569438e3","status":"affected","lessThan":"5d70eb25b41e9b010828cd12818b06a0c3b04412","versionType":"git"},{"version":"8590541473188741055d27b955db0777569438e3","status":"affected","lessThan":"2694d408b0e595024e0fc1d64ff9db0358580f74","versionType":"git"},{"version":"8590541473188741055d27b955db0777569438e3","status":"affected","lessThan":"a9b8b18364fffce4c451e6f6fd218fa4ab646705","versionType":"git"},{"version":"ab6397f072e5097f267abf5cb08a8004e6b17694","status":"affected","versionType":"git"},{"version":"5.15.160","status":"affected","lessThan":"5.15.203","versionType":"semver"},{"version":"6.1.84","status":"affected","lessThan":"6.1.169","versionType":"semver"},{"version":"6.6.18","status":"affected","lessThan":"6.6.135","versionType":"semver"},{"version":"6.7.6","status":"affected","lessThan":"6.8","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/tls/tls_sw.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.8","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.8","versionType":"semver"},{"version":"5.15.203","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.169","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.135","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.82","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.23","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.13","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/tls/tls_sw.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/414fc5e5a5aff776c150f1b86770e0a25a35df3a"},{"url":"https://git.kernel.org/stable/c/02f3ecadb23558bbe068e6504118f1b712d4ece0"},{"url":"https://git.kernel.org/stable/c/0e43e0a3c94044acc74b8e0927c27972eb5a59e8"},{"url":"https://git.kernel.org/stable/c/aa9facde6c5005205874c37db3fd25799d741baf"},{"url":"https://git.kernel.org/stable/c/5d70eb25b41e9b010828cd12818b06a0c3b04412"},{"url":"https://git.kernel.org/stable/c/2694d408b0e595024e0fc1d64ff9db0358580f74"},{"url":"https://git.kernel.org/stable/c/a9b8b18364fffce4c451e6f6fd218fa4ab646705"}],"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 bug is in the kTLS TX path reached when a kTLS-enabled network service sends TLS records to a peer; a remote client can plausibly trigger repeated encrypted responses and connection errors over the network.\nAC:L - The vulnerable condition is the normal async crypto backlog/error path, and an attacker can drive request volume and connection aborts/retries rather than depending on an uncontrollable race. Under the required rule, the defensible choice for a kTLS UAF is low complexity.\nPR:N - In the network-service scenario, the attacker only needs to connect to and interact with the exposed TLS service; no local account or kernel capability is required.\nUI:N - No user interaction is required once the vulnerable kTLS-enabled service is reachable; the attacker can trigger sends by network requests.\nS:U - The corruption is within the kernel handling of the same host and does not cross a separate security authority such as a VM boundary.\nC:H - This is a use-after-free of a heap-allocated tls_rec used later by an async crypto callback, giving memory corruption potential consistent with kernel information disclosure.\nI:H - The async callback writes through fields in the freed record, so heap reuse can turn the UAF into kernel memory corruption/control-flow impact.\nA:H - Even without full exploitation, the stale callback can dereference or modify freed memory and crash or oops the 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