{"id":"CVE-2026-46100","state":"PUBLISHED","title":"fs: afs: revert mmap_prepare() change","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nfs: afs: revert mmap_prepare() change\n\nPartially reverts commit 9d5403b1036c (\"fs: convert most other\ngeneric_file_*mmap() users to .mmap_prepare()\").\n\nThis is because the .mmap invocation establishes a refcount, but\n.mmap_prepare is called at a point where a merge or an allocation failure\nmight happen after the call, which would leak the refcount increment.\n\nFunctionality is being added to permit the use of .mmap_prepare in this\ncase, but in the interim, we need to fix this.","publishedAt":"2026-05-27T12:59:06.853Z","updatedAt":"2026-08-05T12:29:37.582Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"9d5403b1036cdcd4be0f9f5568612c0e60e73d79","status":"affected","lessThan":"f51f85c044809fbd39ac8ae07ac99bc43ce32bd5","versionType":"git"},{"version":"9d5403b1036cdcd4be0f9f5568612c0e60e73d79","status":"affected","lessThan":"48c7a0eaeea41da17d1d84d2d7a4c40be122b246","versionType":"git"},{"version":"9d5403b1036cdcd4be0f9f5568612c0e60e73d79","status":"affected","lessThan":"fbfc6578eaca12daa0c09df1e9ba7f2c657b49da","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/afs/file.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.17","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.17","versionType":"semver"},{"version":"6.18.27","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.4","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/afs/file.c"]}],"references":["https://git.kernel.org/stable/c/f51f85c044809fbd39ac8ae07ac99bc43ce32bd5","https://git.kernel.org/stable/c/48c7a0eaeea41da17d1d84d2d7a4c40be122b246","https://git.kernel.org/stable/c/fbfc6578eaca12daa0c09df1e9ba7f2c657b49da"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:07.131Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/46xxx/CVE-2026-46100.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-46100","state":"PUBLISHED","datePublished":"2026-05-27T12:59:06.853Z","dateUpdated":"2026-08-05T12:29:37.582Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-05-13T15:03:33.097Z"},"containers":{"cna":{"title":"fs: afs: revert mmap_prepare() change","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nfs: afs: revert mmap_prepare() change\n\nPartially reverts commit 9d5403b1036c (\"fs: convert most other\ngeneric_file_*mmap() users to .mmap_prepare()\").\n\nThis is because the .mmap invocation establishes a refcount, but\n.mmap_prepare is called at a point where a merge or an allocation failure\nmight happen after the call, which would leak the refcount increment.\n\nFunctionality is being added to permit the use of .mmap_prepare in this\ncase, but in the interim, we need to fix this."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"9d5403b1036cdcd4be0f9f5568612c0e60e73d79","status":"affected","lessThan":"f51f85c044809fbd39ac8ae07ac99bc43ce32bd5","versionType":"git"},{"version":"9d5403b1036cdcd4be0f9f5568612c0e60e73d79","status":"affected","lessThan":"48c7a0eaeea41da17d1d84d2d7a4c40be122b246","versionType":"git"},{"version":"9d5403b1036cdcd4be0f9f5568612c0e60e73d79","status":"affected","lessThan":"fbfc6578eaca12daa0c09df1e9ba7f2c657b49da","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/afs/file.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.17","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.17","versionType":"semver"},{"version":"6.18.27","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.4","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/afs/file.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/f51f85c044809fbd39ac8ae07ac99bc43ce32bd5"},{"url":"https://git.kernel.org/stable/c/48c7a0eaeea41da17d1d84d2d7a4c40be122b246"},{"url":"https://git.kernel.org/stable/c/fbfc6578eaca12daa0c09df1e9ba7f2c657b49da"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The refcount leak is set up by a local mmap() syscall on a file in a mounted AFS volume; although AFS is a network filesystem, the vulnerable code path is reached via a local syscall, not via remote packet processing.\nAC:L - A local user reliably forces the leaking path by mmap'ing adjacent compatible regions to cause a VMA merge after .mmap_prepare; the merge and the subsequent fileserver-driven open_mmaps traversal are repeatable and within the attacker's control.\nPR:L - Exploitation requires only an unprivileged local account able to open and mmap a readable file on the AFS mount; no elevated capabilities are needed.\nUI:N - The attacker performs the mmap themselves; no action by another user is required (the AFS mount is environmental setup, not interaction).\nS:U - The corrupted vnode and the impacted callback-break code are all within the kernel's own security authority; no boundary such as VM/IOMMU is crossed.\nC:H - The leaked refcount leaves a freed afs_vnode linked on open_mmaps, and a subsequent callback-break traversal yields a use-after-free whose freed slab object can be controlled to enable arbitrary kernel memory disclosure.\nI:H - The use-after-free on the afs_vnode (afs_inode_cachep) permits heap spraying of attacker-controlled contents, providing a write primitive and potential control-flow hijack.\nA:H - The dangling list entry causes kernel oops/panic on the next callback-break traversal, and sustained triggering also leaks vnodes, so availability is fully impacted."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T12:29:37.582Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.17","versionEndExcluding":"6.18.27"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.17","versionEndExcluding":"7.0.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.17","versionEndExcluding":"7.1"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}