{"id":"CVE-2026-74578","title":"crypto: algif_skcipher - force synchronous processing on trees without ctx->state","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\ncrypto: algif_skcipher - force synchronous processing on trees without ctx->state\n\nThe AIO/async path in skcipher_recvmsg() passes the socket-wide ctx->iv\ndirectly into…","severity":"high","cvss":7.1,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= e870456d8e7c8d57c059ea479b5aadbb55ff4c3a < bf09b0be8e851f050e98da702d247c14d81b591a","Linux >= e870456d8e7c8d57c059ea479b5aadbb55ff4c3a < 73dd3bf704ca6c20639de70c08e9a10bee904a95","Linux >= e870456d8e7c8d57c059ea479b5aadbb55ff4c3a < f1a87ca0843d74482402a206ea2dfb315ee9acbd","Linux >= e870456d8e7c8d57c059ea479b5aadbb55ff4c3a < 7b91e51d0eb7cbb07f7f086f9176bd93dbbc85dd","Linux >= e870456d8e7c8d57c059ea479b5aadbb55ff4c3a < 60eafc7b08c6689ea3ad39eff8d97aefc8a087c7","Linux >= e870456d8e7c8d57c059ea479b5aadbb55ff4c3a < d7860b682da55433b5da0591b0e4c1982ecd2689","Linux >= e870456d8e7c8d57c059ea479b5aadbb55ff4c3a < b05defc41b27c7d0c05c45f67bf5b91c28f93669","Linux >= e870456d8e7c8d57c059ea479b5aadbb55ff4c3a < fcc77d33a34cf271702e8daafb6c593e4626776d","Linux 4.14"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-10-16T19:00:58.726885Z"},"published":"2026-08-16","updated":"2026-10-16","sourceUpdated":"2026-10-16T19:05:57.566Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-74578","references":[{"url":"https://git.kernel.org/stable/c/bf09b0be8e851f050e98da702d247c14d81b591a"},{"url":"https://git.kernel.org/stable/c/73dd3bf704ca6c20639de70c08e9a10bee904a95"},{"url":"https://git.kernel.org/stable/c/f1a87ca0843d74482402a206ea2dfb315ee9acbd"},{"url":"https://git.kernel.org/stable/c/7b91e51d0eb7cbb07f7f086f9176bd93dbbc85dd"},{"url":"https://git.kernel.org/stable/c/60eafc7b08c6689ea3ad39eff8d97aefc8a087c7"},{"url":"https://git.kernel.org/stable/c/d7860b682da55433b5da0591b0e4c1982ecd2689"},{"url":"https://git.kernel.org/stable/c/b05defc41b27c7d0c05c45f67bf5b91c28f93669"},{"url":"https://git.kernel.org/stable/c/fcc77d33a34cf271702e8daafb6c593e4626776d"}],"tags":["cve.org"],"epss":0.00194,"epssPercentile":0.0853,"ingestedAt":"2026-10-16T19:46:24.340Z","slug":"CVE-2026-74578","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\ncrypto: algif_skcipher - force synchronous processing on trees without ctx->state\n\nThe AIO/async path in skcipher_recvmsg() passes the socket-wide ctx->iv\ndirectly into the skcipher request. After io_submit() the socket lock is\ndropped and the request is processed asynchronously, so a concurrent\nsendmsg(ALG_SET_IV) can overwrite ctx->iv and make the in-flight request\nrun under an attacker-controlled IV. For CTR/stream modes this is\nIV/keystream reuse and lets an unprivileged user recover the plaintext of\na concurrent operation.\n\nSnapshotting ctx->iv into per-request storage for the async path is not\nsufficient. For ciphers with statesize == 0 - which includes cbc and ctr -\nthe MSG_MORE inter-chunk IV chaining is carried solely by the in-place\nreq->iv writeback, which a snapshot redirects into per-request memory that\naf_alg_free_resources() releases on completion, silently producing wrong\noutput. Writing the IV back from the completion callback instead is not\npossible either: that would require lock_sock() there, but the callback can\nrun in softirq/atomic context, so it must not sleep.\n\nMake the operation synchronous instead, which removes both the IV race and\nany writeback race. This is equivalent to the upstream resolution, commit\nfcc77d33a34c (\"net: Remove support for AIO on sockets\"), which removed the\nAIO socket path across net/ entirely and so produces the same end state for\nthis file. This patch deviates from that commit deliberately: rather than\nremoving AIO socket support tree-wide, which would be far too invasive for\nstable, it removes only the AIO branch in crypto/algif_skcipher.c.\nio_submit() now completes synchronously; AF_ALG async is rarely used in\npractice.\n\nThe -EIOCBQUEUED check in skcipher_recvmsg() is now dead but harmless,\nand is left alone to keep the fix minimal.\n\nTested on 6.6.y: attacker IV injection dropped from 2296/200000 to 0/200000\nafter the change; MSG_MORE chunked CTR output bit-identical to single-shot.\n\n## Affected\n\n- `Linux >= e870456d8e7c8d57c059ea479b5aadbb55ff4c3a < bf09b0be8e851f050e98da702d247c14d81b591a`\n- `Linux >= e870456d8e7c8d57c059ea479b5aadbb55ff4c3a < 73dd3bf704ca6c20639de70c08e9a10bee904a95`\n- `Linux >= e870456d8e7c8d57c059ea479b5aadbb55ff4c3a < f1a87ca0843d74482402a206ea2dfb315ee9acbd`\n- `Linux >= e870456d8e7c8d57c059ea479b5aadbb55ff4c3a < 7b91e51d0eb7cbb07f7f086f9176bd93dbbc85dd`\n- `Linux >= e870456d8e7c8d57c059ea479b5aadbb55ff4c3a < 60eafc7b08c6689ea3ad39eff8d97aefc8a087c7`\n- `Linux >= e870456d8e7c8d57c059ea479b5aadbb55ff4c3a < d7860b682da55433b5da0591b0e4c1982ecd2689`\n- `Linux >= e870456d8e7c8d57c059ea479b5aadbb55ff4c3a < b05defc41b27c7d0c05c45f67bf5b91c28f93669`\n- `Linux >= e870456d8e7c8d57c059ea479b5aadbb55ff4c3a < fcc77d33a34cf271702e8daafb6c593e4626776d`\n- `Linux 4.14`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":39,"depthScoreParts":{"impact":39.1,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}