CVE-2026-68099 (GCVE-0-2026-68099)
Vulnerability from cvelistv5
Published
2026-08-10 11:58
Modified
2026-08-23 12:45
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
ksmbd: restore DACL size on check_add_overflow() to avoid malformed ACL
check_add_overflow() unconditionally writes the truncated sum into *d
even on overflow, per its contract in include/linux/overflow.h.
The four check_add_overflow() guards in set_posix_acl_entries_dacl()
and set_ntacl_dacl() break out of the ACE-building loops on overflow,
but the truncated *size is then consumed downstream at the end of
set_ntacl_dacl():
pndacl->size = cpu_to_le16(le16_to_cpu(pndacl->size) + size);
This produces an on-wire NT ACL whose pndacl->size under-reports the
bytes actually written by the preceding fill_ace_for_sid()/memcpy()
calls, yielding a malformed ACL that can trigger out-of-bounds reads
when re-parsed by clients or ksmbd itself.
Restore *size to its pre-addition value on each overflow branch (via
`*size -= ace_sz` / `size -= nt_ace_size`) so that after the break,
*size once again holds the cumulative size of the successfully-written
ACEs. The committed ACL is then truncated-but-self-consistent rather
than malformed.
The ksmbd DACL builders are the only check_add_overflow() sites found
where an overflow path breaks out of a loop and the destination value
is consumed afterward. The other nearby break-style cases either
return -EINVAL on overflow (transport_ipc.c) or break without
consuming the overflowed destination value afterward (buildid.c).
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: 41e53a773db6342ac9a689ee5ba635c31744c9f0 Version: 8d5729350b236896f51379588d9a690b7fafb8db Version: e1955a94b6f17f4b058afa955a6f187eb3ed7615 Version: 5e7b8f3c539d69b2ed5f2408e2f75e68ce7eef43 Version: 299f962c0b02d048fb45d248b4da493d03f3175d Version: 299f962c0b02d048fb45d248b4da493d03f3175d Version: ef7902be3f215b6bf7babe4dc9dd9a7d57dad7a7 Version: 6.1.175 ≤ Version: 6.6.136 ≤ Version: 6.12.84 ≤ Version: 6.18.25 ≤ Version: 7.0.2 ≤ |
||
{
"containers": {
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"programFiles": [
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],
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},
{
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"status": "unaffected",
"version": "0",
"versionType": "semver"
},
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},
{
"lessThanOrEqual": "6.12.*",
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},
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{
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{
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"versionType": "original_commit_for_fix"
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]
}
],
"cpeApplicability": [
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],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: restore DACL size on check_add_overflow() to avoid malformed ACL\n\ncheck_add_overflow() unconditionally writes the truncated sum into *d\neven on overflow, per its contract in include/linux/overflow.h.\nThe four check_add_overflow() guards in set_posix_acl_entries_dacl()\nand set_ntacl_dacl() break out of the ACE-building loops on overflow,\nbut the truncated *size is then consumed downstream at the end of\nset_ntacl_dacl():\n\n pndacl-\u003esize = cpu_to_le16(le16_to_cpu(pndacl-\u003esize) + size);\n\nThis produces an on-wire NT ACL whose pndacl-\u003esize under-reports the\nbytes actually written by the preceding fill_ace_for_sid()/memcpy()\ncalls, yielding a malformed ACL that can trigger out-of-bounds reads\nwhen re-parsed by clients or ksmbd itself.\n\nRestore *size to its pre-addition value on each overflow branch (via\n`*size -= ace_sz` / `size -= nt_ace_size`) so that after the break,\n*size once again holds the cumulative size of the successfully-written\nACEs. The committed ACL is then truncated-but-self-consistent rather\nthan malformed.\n\nThe ksmbd DACL builders are the only check_add_overflow() sites found\nwhere an overflow path breaks out of a loop and the destination value\nis consumed afterward. The other nearby break-style cases either\nreturn -EINVAL on overflow (transport_ipc.c) or break without\nconsuming the overflowed destination value afterward (buildid.c)."
}
],
"providerMetadata": {
"dateUpdated": "2026-08-23T12:45:49.075Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/8f3a7a499a7d9bb1c0f33fe78c4a4594d7e307f4"
},
{
"url": "https://git.kernel.org/stable/c/f4fcd0c1a243d449307b887fafee23921e9db5ab"
},
{
"url": "https://git.kernel.org/stable/c/0bf38372821b1526f31538a7d9811844c55c7f38"
},
{
"url": "https://git.kernel.org/stable/c/847ecd4eb3c117c3d2f13f1e7ab506543aad8183"
},
{
"url": "https://git.kernel.org/stable/c/bc90144ce8bb7fcf05ad9417c7adb4e9509d9e13"
},
{
"url": "https://git.kernel.org/stable/c/bbf0a8e931204ecdab494a88d43b0a24a04285c5"
}
],
"title": "ksmbd: restore DACL size on check_add_overflow() to avoid malformed ACL",
"x_generator": {
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}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-68099",
"datePublished": "2026-08-10T11:58:13.940Z",
"dateReserved": "2026-07-30T09:28:09.368Z",
"dateUpdated": "2026-08-23T12:45:49.075Z",
"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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