smb: client: fix ALIGN() overflow in symlink_data() error context loop
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- High · None · High
- Fix status
- Partial Red Hat: 4 without a fix
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat.
Summary
In the Linux kernel, the following vulnerability has been resolved: smb: client: fix ALIGN() overflow in symlink_data() error context loop The check added by commit 7d9a7f1f96cd ("smb/client: fix possible infinite loop and oob read in symlink_data()") compared the post-ALIGN length against the remaining buffer, but ALIGN() itself can overflow: for ErrorDataLength near UINT32_MAX (e.g. 0xFFFFFFF9), ALIGN(x, 8) wraps to 0, so the subsequent bounds check passes, and the loop advances by zero bytes leaving 'p' pointing into stale data. Fix by checking the raw ErrorDataLength against the remaining space before applying ALIGN(), then checking again after. Since raw_len is bounded by the buffer, raw_len + 7 cannot overflow, so the second check is an exact post-alignment bounds guard.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
Remediation
- Fix · CNA Linux (Linux) Fixed in 6.1
- Fix · CNA Linux (Linux) Fixed in 6.1.188, 6.6.157, 6.12.109, 6.18.50, 7.2.4, 7.3
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 9 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 4 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 5 | Affected | No fix yet: Fix deferred |
Not affected: 5 products
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
- Red Hat OpenShift Container Platform 4
Timeline
- 2026-10-02 Threatist record created from CVE-2026-89634
- 2026-10-03 Alias added: GHSA-959h-4fxq-gqhj
- 2026-10-19 Fix available: Linux/[email protected] · CNA
- 2026-10-21 Affected versions changed · Red Hat
- 2026-10-21 CVSS score changed · Red Hat
- 2026-10-29 Affected versions changed · Red Hat
- 2026-11-06 Affected versions changed · Red Hat
References
Other 6
- https://git.kernel.org/stable/c/2b4a25baa0b936fef6915c0459925077b324ecaf
- https://git.kernel.org/stable/c/b89d678f9eafcf8d74885983166ba26b40a04ea0
- https://git.kernel.org/stable/c/657372ba6ea50b4474d2a6a610097eae8cd1f3e9
- https://git.kernel.org/stable/c/1f824f61d1df52392eaf0b74dfa5659d724fde30
- https://git.kernel.org/stable/c/62a3025983c8c735a3c6fc85a59316f31b59af07
- https://git.kernel.org/stable/c/62656b024efc21c3230eade1a847f25871c3d2bb
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Sources
- CVE-2026-89634 · CVE Program
- CVE-2026-89634 · NVD
- FIRST EPSS
- GHSA-959h-4fxq-gqhj · GitHub Advisory Database · CC BY 4.0
- CVE-2026-89634 · Red Hat security data · CC BY 4.0
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