CVE-2026-74578: Software Security Vulnerability Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-fh4p-v6r7-6956",
  "modified" : "2026-08-17T06:33:55Z",
  "published" : "2026-08-16T09:30:22Z",
  "aliases" : [ "CVE-2026-74578" ],
  "details" : "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.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N"
  } ],
  "affected" : [ ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-74578"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/60eafc7b08c6689ea3ad39eff8d97aefc8a087c7"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/73dd3bf704ca6c20639de70c08e9a10bee904a95"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/7b91e51d0eb7cbb07f7f086f9176bd93dbbc85dd"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/b05defc41b27c7d0c05c45f67bf5b91c28f93669"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/bf09b0be8e851f050e98da702d247c14d81b591a"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/d7860b682da55433b5da0591b0e4c1982ecd2689"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/f1a87ca0843d74482402a206ea2dfb315ee9acbd"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/fcc77d33a34cf271702e8daafb6c593e4626776d"
  } ],
  "database_specific" : {
    "cwe_ids" : [ ],
    "severity" : "HIGH",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-08-16T09:16:21Z"
  }
}