{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2021-47496", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-05-22T06:20:56.202Z", "datePublished": "2024-05-22T08:19:43.489Z", "dateUpdated": "2026-08-05T08:48:05.957Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T08:48:05.957Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/tls: Fix flipped sign in tls_err_abort() calls\n\nsk->sk_err appears to expect a positive value, a convention that ktls\ndoesn't always follow and that leads to memory corruption in other code.\nFor instance,\n\n [kworker]\n tls_encrypt_done(..., err=)\n tls_err_abort(.., err)\n sk->sk_err = err;\n\n [task]\n splice_from_pipe_feed\n ...\n tls_sw_do_sendpage\n if (sk->sk_err) {\n ret = -sk->sk_err; // ret is positive\n\n splice_from_pipe_feed (continued)\n ret = actor(...) // ret is still positive and interpreted as bytes\n // written, resulting in underflow of buf->len and\n // sd->len, leading to huge buf->offset and bogus\n // addresses computed in later calls to actor()\n\nFix all tls_err_abort() callers to pass a negative error code\nconsistently and centralize the error-prone sign flip there, throwing in\na warning to catch future misuse and uninlining the function so it\nreally does only warn once." } ], "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 kTLS (net/tls): a remote peer of a kTLS-offloaded service can set a negative sk_err via tls_read_size()/tls_decrypt_done() by sending a malformed TLS record, then the server’s ordinary sendfile/splice TX path (tls_sw_do_sendpage) mis-handles that sk_err; per guidance, kTLS bugs driven by remote peer data are Network.\nAC:L - The attacker fully controls the malformed TLS records and can send them while the server is mid-sendfile/splice (or retry across connections); no race or memory-layout condition outside attacker influence is required for the sign-flip corruption.\nPR:N - An unauthenticated client of a public kTLS HTTPS/TLS service needs no account or capability on the host; setsockopt(TCP_ULP,\"tls\")/TLS_TX|RX also requires no capability once the tls module is loaded.\nUI:N - Exploitation needs only the attacker’s TLS traffic plus the server’s normal sendfile/splice response path; no separate victim user or administrator action is required.\nS:U - The pipe-buffer underflow and resulting UAF/OOB access corrupt kernel memory within the same host kernel authority and do not cross a VM, IOMMU, or sandbox boundary.\nC:H - splice_from_pipe_feed underflows buf->len and advances buf->offset into bogus addresses, and syzbot observed a KASAN use-after-free read in __crypto_xor; that memory-corruption/UAF primitive is leverageable for arbitrary kernel disclosure.\nI:H - The same underflow drives later actor()/sendpage calls with huge offsets into reclaimed or adjacent memory, yielding OOB write and UAF write primitives that can be escalated to control-flow hijack.\nA:H - The resulting use-after-free and out-of-bounds accesses reliably oops/panic the kernel (as in the syzbot KASAN report), fully disrupting availability." } ] } ], "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_sw.c" ], "versions": [ { "version": "c46234ebb4d1eee5e09819f49169e51cfc6eb909", "lessThan": "e0cfd5159f314d6b304d030363650b06a2299cbb", "status": "affected", "versionType": "git" }, { "version": "c46234ebb4d1eee5e09819f49169e51cfc6eb909", "lessThan": "f3dec7e7ace38224f82cf83f0049159d067c2e19", "status": "affected", "versionType": "git" }, { "version": "c46234ebb4d1eee5e09819f49169e51cfc6eb909", "lessThan": "e41473543f75f7dbc5d605007e6f883f1bd13b9a", "status": "affected", "versionType": "git" }, { "version": "c46234ebb4d1eee5e09819f49169e51cfc6eb909", "lessThan": "da353fac65fede6b8b4cfe207f0d9408e3121105", "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_sw.c" ], "versions": [ { "version": "4.17", "status": "affected" }, { "version": "0", "lessThan": "4.17", "status": "unaffected", "versionType": "semver" }, { "version": "5.4.157", "lessThanOrEqual": "5.4.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.77", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.14.16", "lessThanOrEqual": "5.14.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15", "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": "4.17", "versionEndExcluding": "5.4.157" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.17", "versionEndExcluding": "5.10.77" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.17", "versionEndExcluding": "5.14.16" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.17", "versionEndExcluding": "5.15" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/e0cfd5159f314d6b304d030363650b06a2299cbb" }, { "url": "https://git.kernel.org/stable/c/f3dec7e7ace38224f82cf83f0049159d067c2e19" }, { "url": "https://git.kernel.org/stable/c/e41473543f75f7dbc5d605007e6f883f1bd13b9a" }, { "url": "https://git.kernel.org/stable/c/da353fac65fede6b8b4cfe207f0d9408e3121105" } ], "title": "net/tls: Fix flipped sign in tls_err_abort() calls", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2024-08-04T05:39:59.752Z" }, "title": "CVE Program Container", "references": [ { "url": "https://git.kernel.org/stable/c/e0cfd5159f314d6b304d030363650b06a2299cbb", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/f3dec7e7ace38224f82cf83f0049159d067c2e19", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/e41473543f75f7dbc5d605007e6f883f1bd13b9a", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/da353fac65fede6b8b4cfe207f0d9408e3121105", "tags": [ "x_transferred" ] } ] }, { "metrics": [ { "other": { "type": "ssvc", "content": { "id": "CVE-2021-47496", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "partial" } ], "version": "2.0.3", "timestamp": "2024-09-10T15:35:52.280096Z" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2024-09-11T17:33:23.659Z" } } ] } }