{"cve":"CVE-2026-74578","nvd":{"published":"2026-08-16T09:16:21.653","modified":"2026-10-16T20:17:39.407","status":"Received","description":"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 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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N","score":7.1},"cwes":[],"references":["https://git.kernel.org/stable/c/60eafc7b08c6689ea3ad39eff8d97aefc8a087c7","https://git.kernel.org/stable/c/73dd3bf704ca6c20639de70c08e9a10bee904a95","https://git.kernel.org/stable/c/7b91e51d0eb7cbb07f7f086f9176bd93dbbc85dd","https://git.kernel.org/stable/c/b05defc41b27c7d0c05c45f67bf5b91c28f93669","https://git.kernel.org/stable/c/bf09b0be8e851f050e98da702d247c14d81b591a"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:49:10.689564601+00:00"},"epss":{"cve":"CVE-2026-74578","score":0.00194,"percentile":0.09046,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}