CVE-2026-74350 (GCVE-0-2026-74350)
Vulnerability from cvelistv5
Published
2026-08-15 05:58
Modified
2026-08-17 05:46
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
ocfs2: validate fast symlink target during inode read
ocfs2_validate_inode_block() already rejects several inconsistent
self-contained dinodes before they are exposed to the rest of the
filesystem. Fast symlinks need the same treatment.
A zero-cluster symlink is treated as a fast symlink and later read through
page_get_link() and ocfs2_fast_symlink_read_folio(). That path uses
strnlen() on the inline payload and then copies len + 1 bytes into the
folio. If a corrupt dinode stores an i_size that does not fit the inline
area or omits the terminating NUL at i_size, that copy reads past the end
of the inode block buffer.
Reject zero-cluster symlink dinodes whose i_size exceeds the inline
fast-symlink capacity or whose inline payload is not NUL-terminated
exactly at i_size when the inode block is validated. This keeps malformed
fast symlinks from reaching the read path.
Validation reproduced this kernel report:
KASAN use-after-free in ocfs2_fast_symlink_read_folio+0x12c/0x1f0
RIP: 0033:0x7f5c6d859aa7
Read of size 3905
Call trace:
dump_stack_lvl+0x66/0xa0 (?:?)
print_report+0xce/0x630 (?:?)
ocfs2_fast_symlink_read_folio+0x12c/0x1f0 (fs/ocfs2/inode.c:?)
srso_alias_return_thunk+0x5/0xfbef5 (?:?)
__virt_addr_valid+0x19f/0x330 (?:?)
kasan_report+0xe0/0x110 (?:?)
kasan_check_range+0x105/0x1b0 (?:?)
__asan_memcpy+0x23/0x60 (?:?)
filemap_read_folio+0x27/0xe0 (?:?)
filemap_read_folio+0x35/0xe0 (?:?)
do_read_cache_folio+0x138/0x230 (?:?)
__page_get_link+0x26/0x110 (?:?)
page_get_link+0x2e/0x70 (?:?)
vfs_readlink+0x15e/0x250 (?:?)
touch_atime+0x4d/0x370 (?:?)
do_readlinkat+0x186/0x200 (?:?)
do_user_addr_fault+0x65a/0x890 (?:?)
__x64_sys_readlink+0x46/0x60 (?:?)
do_syscall_64+0x115/0x6a0 (arch/x86/entry/syscall_64.c:87)
entry_SYSCALL_64_after_hwframe+0x77/0x7f (?:?)
References
Impacted products
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"fs/ocfs2/inode.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
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"status": "affected",
"version": "ea022dfb3c2a4680483b00eb2fecc9fc4f6091d1",
"versionType": "git"
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{
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"status": "affected",
"version": "ea022dfb3c2a4680483b00eb2fecc9fc4f6091d1",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"fs/ocfs2/inode.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "3.5"
},
{
"lessThan": "3.5",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
"version": "7.1.5",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.1.5",
"versionStartIncluding": "3.5",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.2",
"versionStartIncluding": "3.5",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nocfs2: validate fast symlink target during inode read\n\nocfs2_validate_inode_block() already rejects several inconsistent\nself-contained dinodes before they are exposed to the rest of the\nfilesystem. Fast symlinks need the same treatment.\n\nA zero-cluster symlink is treated as a fast symlink and later read through\npage_get_link() and ocfs2_fast_symlink_read_folio(). That path uses\nstrnlen() on the inline payload and then copies len + 1 bytes into the\nfolio. If a corrupt dinode stores an i_size that does not fit the inline\narea or omits the terminating NUL at i_size, that copy reads past the end\nof the inode block buffer.\n\nReject zero-cluster symlink dinodes whose i_size exceeds the inline\nfast-symlink capacity or whose inline payload is not NUL-terminated\nexactly at i_size when the inode block is validated. This keeps malformed\nfast symlinks from reaching the read path.\n\nValidation reproduced this kernel report:\nKASAN use-after-free in ocfs2_fast_symlink_read_folio+0x12c/0x1f0\nRIP: 0033:0x7f5c6d859aa7\nRead of size 3905\nCall trace:\n dump_stack_lvl+0x66/0xa0 (?:?)\n print_report+0xce/0x630 (?:?)\n ocfs2_fast_symlink_read_folio+0x12c/0x1f0 (fs/ocfs2/inode.c:?)\n srso_alias_return_thunk+0x5/0xfbef5 (?:?)\n __virt_addr_valid+0x19f/0x330 (?:?)\n kasan_report+0xe0/0x110 (?:?)\n kasan_check_range+0x105/0x1b0 (?:?)\n __asan_memcpy+0x23/0x60 (?:?)\n filemap_read_folio+0x27/0xe0 (?:?)\n filemap_read_folio+0x35/0xe0 (?:?)\n do_read_cache_folio+0x138/0x230 (?:?)\n __page_get_link+0x26/0x110 (?:?)\n page_get_link+0x2e/0x70 (?:?)\n vfs_readlink+0x15e/0x250 (?:?)\n touch_atime+0x4d/0x370 (?:?)\n do_readlinkat+0x186/0x200 (?:?)\n do_user_addr_fault+0x65a/0x890 (?:?)\n __x64_sys_readlink+0x46/0x60 (?:?)\n do_syscall_64+0x115/0x6a0 (arch/x86/entry/syscall_64.c:87)\n entry_SYSCALL_64_after_hwframe+0x77/0x7f (?:?)"
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 9.8,
"baseSeverity": "CRITICAL",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:N - OCFS2 cluster nodes commonly NFS-export shared LUNs; nfsd READLINK reaches vfs_readlink\u2192page_get_link\u2192ocfs2_fast_symlink_read_folio on a forged zero-cluster symlink dinode on the volume, giving a remote network attack path without a local syscall.\nAC:L - A forged dinode fully controls i_size and inline bytes; strnlen() bounded only by ocfs2_fast_symlink_chars() then memcpy_to_folio() copies len+1 past the inode buffer_head (KASAN read ~3905), deterministically and without races.\nPR:N - Triggering needs only permission to read the symlink: a remote NFS client on an exported share, or any unprivileged local/cluster user; planting the malformed dinode uses attacker-controlled on-disk metadata on shared storage, not init-namespace root on the victim.\nUI:N - Once the corrupt fast symlink exists on a mounted/exported volume, readlink(2), NFS READLINK, or path lookup via get_link automatically pulls the inline target through ocfs2_fast_symlink_read_folio with no further deliberate victim action.\nS:U - Impact stays within the host kernel parsing the OCFS2 symlink (memory disclosure/crash/privilege escalation on the server); no VM escape, IOMMU bypass, or cross-authority scope change.\nC:H - memcpy_to_folio() performs an out-of-bounds read up to ~3900 bytes past the inode block buffer (KASAN UAF/slab read of size 3905); OOB/UAF kernel reads enable arbitrary adjacent-heap disclosure.\nI:H - The same unvalidated strnlen/memcpy path corrupts kernel memory semantics (KASAN UAF) and, per kernel CNA guidance, UAF/OOB reads adjacent slab objects can be leveraged into write/control-flow primitives via heap grooming.\nA:H - KASAN reports use-after-free in ocfs2_fast_symlink_read_folio during the over-wide memcpy; such kernel memory faults typically oops/panic the host, fully denying availability."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-17T05:46:13.886Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/f9e2cb692b77a679b1f4cc2b7b277fa908586533"
},
{
"url": "https://git.kernel.org/stable/c/e234973f286ed2e8961a24561ec91594ec3e3ff8"
}
],
"title": "ocfs2: validate fast symlink target during inode read",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-74350",
"datePublished": "2026-08-15T05:58:37.298Z",
"dateReserved": "2026-08-15T05:44:03.886Z",
"dateUpdated": "2026-08-17T05:46:13.886Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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