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CVE

CVE-2026-89634

smb: client: fix ALIGN() overflow in symlink_data() error context loop
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CVE

CVE-2026-89634

smb: client: fix ALIGN() overflow in symlink_data() error context loop

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.

Package Versions Affected

Package Version
patch Availability
No items found.

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CVSS Version

Severity
Base Score
CVSS Version
Score Vector
C
H
U
9.1
-
3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
C
H
U
0
-
3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
C
H
U
-

Related Resources

No items found.

References

https://git.kernel.org/stable/c/1f824f61d1df52392eaf0b74dfa5659d724fde30, https://git.kernel.org/stable/c/2b4a25baa0b936fef6915c0459925077b324ecaf, https://git.kernel.org/stable/c/62656b024efc21c3230eade1a847f25871c3d2bb, https://git.kernel.org/stable/c/62a3025983c8c735a3c6fc85a59316f31b59af07, https://git.kernel.org/stable/c/657372ba6ea50b4474d2a6a610097eae8cd1f3e9, https://git.kernel.org/stable/c/b89d678f9eafcf8d74885983166ba26b40a04ea0, https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89634.json, https://nvd.nist.gov/vuln/detail/CVE-2026-89634, https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git

Severity

9.1

CVSS Score
0
10

Basic Information

Base CVSS
9.1
EPSS Probability
0.00693%
EPSS Percentile
0.51429%
Introduced Version
76894f3e2f71177747b8b4763fb180e800279585,6.0.16,2d046892a493d9760c35fdaefc3017f27f91b621,6.1.0,6.2.0,6.7.0,6.13.0,6.19.0,0
Fix Available
62656b024efc21c3230eade1a847f25871c3d2bb,6.1,6.1.188,6.6.157,6.12.109,6.18.50,7.2.4,6.12.111-1~deb12u1,6.12.111-1,0:6.12.0-207.111.5.1.el10uek,0:6.12.0-207.111.5.1.el9uek

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