{"id":"CVE-2026-74689","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-74689","summary":"net/atm: fix slab-out-of-bounds read in vcc_setsockopt()","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/atm: fix slab-out-of-bounds read in vcc_setsockopt()\n\nvcc_setsockopt() contained an ineffective optlen check:\n  if (__SO_LEVEL_MATCH(optname, level) && optlen != __SO_SIZE(optname))\n      return -EINVAL;\n\nIf __SO_LEVEL_MATCH(optname, level) evaluated to false (e.g. if the caller\npassed a mismatched level), the length check optlen != __SO_SIZE(optname)\nwas short-circuited and bypassed. Execution then fell through to switch(optname),\ncalling copy_from_sockptr() assuming optval contained sufficient space.\n\nFurthermore, even if level matched, a cgroup BPF setsockopt filter could shrink\noptlen after entry. Because copy_from_sockptr() on kernel pointers uses memcpy(),\nthis leads to a KASAN slab-out-of-bounds read when optlen is smaller than the\nexpected structure size.\n\nFix this by using copy_safe_from_sockptr(), which unconditionally validates\nthat optlen is at least the expected size before copying. Also change the local\n'value' variable type from 'unsigned long' to 'int' so that SO_SETCLP matches\nits sizeof(int) ABI encoding on 64-bit systems.","published":"2026-08-22T15:32:54.034Z","modified":"2026-08-24T11:47:20.647780319Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"Linux","name":"Kernel","fixedVersion":"6.1.183"}],"fix":null,"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/2c5988c7349c0b64a7e0441bfc6e1dca54f7116a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/35f258fee9ed358c6d0f57f91c30bf029c3724af"},{"type":"WEB","url":"https://git.kernel.org/stable/c/6eb6af88710977eb529b558a07294874d8c40c4d"},{"type":"WEB","url":"https://git.kernel.org/stable/c/9f77c1ab382188f5b51982fab6d913443b6dc59f"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b3bcd5d65ac03c15787b2a5b36c718e26a689336"},{"type":"WEB","url":"https://git.kernel.org/stable/c/d0c80dbb970439bd2eeb0e5effff8c16a5f4e1e3"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74689.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-74689"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-24T11:47:20.647780319Z"}}