{"id":"CVE-2026-74689","state":"PUBLISHED","title":"net/atm: fix slab-out-of-bounds read in vcc_setsockopt()","description":"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.","publishedAt":"2026-08-22T15:32:54.034Z","updatedAt":"2026-10-16T19:16:09.361Z","severity":{"score":7.1,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"b3bcd5d65ac03c15787b2a5b36c718e26a689336","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"35f258fee9ed358c6d0f57f91c30bf029c3724af","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"6eb6af88710977eb529b558a07294874d8c40c4d","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"9f77c1ab382188f5b51982fab6d913443b6dc59f","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"2c5988c7349c0b64a7e0441bfc6e1dca54f7116a","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"d0c80dbb970439bd2eeb0e5effff8c16a5f4e1e3","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/atm/common.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.12","versionType":"semver"},{"version":"6.1.183","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.152","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.104","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.45","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.9","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/atm/common.c"]}],"references":["https://git.kernel.org/stable/c/b3bcd5d65ac03c15787b2a5b36c718e26a689336","https://git.kernel.org/stable/c/35f258fee9ed358c6d0f57f91c30bf029c3724af","https://git.kernel.org/stable/c/6eb6af88710977eb529b558a07294874d8c40c4d","https://git.kernel.org/stable/c/9f77c1ab382188f5b51982fab6d913443b6dc59f","https://git.kernel.org/stable/c/2c5988c7349c0b64a7e0441bfc6e1dca54f7116a","https://git.kernel.org/stable/c/d0c80dbb970439bd2eeb0e5effff8c16a5f4e1e3"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:58.252Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/74xxx/CVE-2026-74689.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-74689","state":"PUBLISHED","datePublished":"2026-08-22T15:32:54.034Z","dateUpdated":"2026-10-16T19:16:09.361Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-08-15T05:44:03.926Z"},"containers":{"cna":{"title":"net/atm: fix slab-out-of-bounds read in vcc_setsockopt()","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"b3bcd5d65ac03c15787b2a5b36c718e26a689336","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"35f258fee9ed358c6d0f57f91c30bf029c3724af","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"6eb6af88710977eb529b558a07294874d8c40c4d","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"9f77c1ab382188f5b51982fab6d913443b6dc59f","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"2c5988c7349c0b64a7e0441bfc6e1dca54f7116a","versionType":"git"},{"version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","status":"affected","lessThan":"d0c80dbb970439bd2eeb0e5effff8c16a5f4e1e3","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/atm/common.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.12","versionType":"semver"},{"version":"6.1.183","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.152","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.104","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.45","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.9","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/atm/common.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/b3bcd5d65ac03c15787b2a5b36c718e26a689336"},{"url":"https://git.kernel.org/stable/c/35f258fee9ed358c6d0f57f91c30bf029c3724af"},{"url":"https://git.kernel.org/stable/c/6eb6af88710977eb529b558a07294874d8c40c4d"},{"url":"https://git.kernel.org/stable/c/9f77c1ab382188f5b51982fab6d913443b6dc59f"},{"url":"https://git.kernel.org/stable/c/2c5988c7349c0b64a7e0441bfc6e1dca54f7116a"},{"url":"https://git.kernel.org/stable/c/d0c80dbb970439bd2eeb0e5effff8c16a5f4e1e3"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H","baseScore":7.1,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The bug is reached only via the local setsockopt(2) syscall on an AF_ATMPVC/AF_ATMSVC socket (do_sock_setsockopt -> pvc_setsockopt/svc_setsockopt -> vcc_setsockopt); no remote ATM packet or network-facing handler invokes this path.\nAC:L - The attacker fully controls level, optname, and optlen; passing a mismatched level bypasses the short-circuited length check, and cgroup BPF setsockopt can shrink optlen after entry, deterministically triggering a full-size memcpy past a small kmalloc buffer with no race.\nPR:L - No capability check guards SO_ATMQOS or SO_SETCLP on unconnected ATM sockets; any unprivileged local user in init_net (required because ATM socket creation rejects non-init network namespaces) can open AF_ATMPVC sockets and issue the crafted setsockopt without CAP_NET_ADMIN.\nUI:N - The attacker triggers the out-of-bounds read entirely from their own process with a single crafted setsockopt call; no victim interaction or cooperation is required.\nS:U - Impact is kernel heap memory disclosure and potential crash within the host kernel security boundary; no VM escape, IOMMU bypass, or cross-sandbox boundary crossing occurs.\nC:H - copy_from_sockptr() performs a slab-out-of-bounds read of up to 92 bytes (struct atm_qos) or 8 bytes (SO_SETCLP) past a kmalloc buffer into kernel stack memory; adjacent slab contents can populate vcc->qos and be retrieved via subsequent SO_ATMQOS getsockopt.\nI:N - The defect is a pure out-of-bounds read with no arbitrary kernel write, heap corruption, or control-flow hijack primitive; although leaked bytes may influence vcc->qos if validation passes, no attacker-controlled data modification occurs.\nA:H - The KASAN-reported slab-out-of-bounds read triggers kernel oops on hardened kernels, and reading past a small kmalloc object into adjacent slab memory on production kernels risks faulting on unmapped redzone pages or corrupting adjacent objects leading to panic."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-25T05:41:33.932Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.1.183"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.6.152"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.12.104"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"6.18.45"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"7.1.9"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.12","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-74689","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"version":"2.0.3","timestamp":"2026-10-16T19:14:36.506932Z"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-16T19:16:09.361Z"}}]}}}