ksmbd: fix OOB write in QUERY_INFO for compound requests
Summary
| CVE | CVE-2026-31432 |
|---|---|
| State | PUBLISHED |
| Assigner | Linux |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-04-22 09:16:21 UTC |
| Updated | 2026-04-27 14:16:38 UTC |
| Description | In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix OOB write in QUERY_INFO for compound requests When a compound request such as READ + QUERY_INFO(Security) is received, and the first command (READ) consumes most of the response buffer, ksmbd could write beyond the allocated buffer while building a security descriptor. The root cause was that smb2_get_info_sec() checked buffer space using ppntsd_size from xattr, while build_sec_desc() often synthesized a significantly larger descriptor from POSIX ACLs. This patch introduces smb_acl_sec_desc_scratch_len() to accurately compute the final descriptor size beforehand, performs proper buffer checking with smb2_calc_max_out_buf_len(), and uses exact-sized allocation + iov pinning. |
Risk And Classification
Primary CVSS: v3.1 8.8 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS: 0.000080000 probability, percentile 0.006920000 (date 2026-04-27)
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | Secondary | 8.8 | HIGH | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | CNA | DECLARED | 8.8 | HIGH | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
CVSS v3.1 Breakdown
Attack Vector
NetworkAttack Complexity
LowPrivileges Required
LowUser Interaction
NoneScope
UnchangedConfidentiality
HighIntegrity
HighAvailability
HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Linux | Linux | affected e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d d48c64fb80ad78b3dd29fb7d79b6ec7bd72bfc09 git | Not specified |
| CNA | Linux | Linux | affected e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d 075ea208c648cc2bcd616295b711d3637c61de45 git | Not specified |
| CNA | Linux | Linux | affected e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d 515c2daab46021221bdf406bef19bc90a44ec617 git | Not specified |
| CNA | Linux | Linux | affected e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d fda9522ed6afaec45cabc198d8492270c394c7bc git | Not specified |
| CNA | Linux | Linux | affected f2283680a80571ca82d710bc6ecd8f8beac67d63 git | Not specified |
| CNA | Linux | Linux | affected 9f297df20d93411c0b4ddad7f88ba04a7cd36e77 git | Not specified |
| CNA | Linux | Linux | affected 6.6 | Not specified |
| CNA | Linux | Linux | unaffected 6.6 semver | Not specified |
| CNA | Linux | Linux | unaffected 6.12.81 6.12.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.18.22 6.18.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.19.12 6.19.* semver | Not specified |
| CNA | Linux | Linux | unaffected 7.0 * original_commit_for_fix | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| git.kernel.org/stable/c/075ea208c648cc2bcd616295b711d3637c61de45 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/d48c64fb80ad78b3dd29fb7d79b6ec7bd72bfc09 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/515c2daab46021221bdf406bef19bc90a44ec617 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/fda9522ed6afaec45cabc198d8492270c394c7bc | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.