9.1

CVE-2026-74521: ksmbd: use memcmp() to compare ClientGUIDs

Received
AliasesUBUNTU-CVE-2026-74521DEBIAN-CVE-2026-74521
Published 15-08-2026Last modified 03-10-2026

Vulnerability summary

CVE-2026-74521 is a critical (CVSS 9.1) vulnerability in linux. EPSS estimates a 0.41% chance of exploitation in the next 30 days, higher than 35% of scored vulnerabilities.

Priority
Prioritisesevere

Severe, CVSS 9.1 (CVE.org); no exploitation reported by the 5 checked sources; EPSS 0% (FIRST, 05-11-2026)

Source freshness unavailable

How is this decided?
CVSS score
9.1/10
010
Critical · v3.1 (CVE.org)
EPSS score
0.41%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 3 · Related 1
USN-8781-1USN-8959-1USN-8960-1

Timeline

  1. 15-08-2026
    PublishedVulnerability first disclosed.
  2. 03-10-2026
    Last modifiedVulnerability information updated.

Description

In the Linux kernel, the following vulnerability has been resolved: ksmbd: use memcmp() to compare ClientGUIDs ClientGUID is a fixed-size binary value and can contain embedded NUL bytes. strncmp() stops comparing at the first NUL byte, so different ClientGUID values can incorrectly be treated as equal. Use memcmp() in SMB3 multichannel session binding and FSCTL_VALIDATE_NEGOTIATE_INFO to compare all SMB2_CLIENT_GUID_SIZE bytes.

CVSS metrics

5 scores · 4 sources · 2 versions

EPSS trend

Probability

0.41%

Chance of exploitation in the next 30 days

Percentile

35%

Versus all other CVEs

30-day change

No change 0.00 pp

From 0.41% on 06-10-2026

06-10-202605-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

No weakness data has been published for this record.

Affected systems

Version check

Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.

Ubuntu157 products
  • linuxAll versions (No fix recorded) | < 7.0.0-42.42
  • linux-allwinner-5.19All versions (No fix recorded)
  • linux-awsAll versions (No fix recorded) | < 7.0.0-1016.17
  • linux-aws-5.0All versions (No fix recorded)
  • linux-aws-5.11All versions (No fix recorded)
Debian2 products
  • linuxAll versions (No fix recorded) | < 6.1.190-1 | < 6.12.111-1 | < 7.1.8-1
  • linux-6.12< 6.12.111-1~deb12u1
Linux1 product
  • linux≥ e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9, < 7bde6f181fa307d2cc1ec2b0313ac8e9811c8232 | ≥ e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9, < 5a0367bf5ce420be7b19936def2e90adcf32a683 | ≥ e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9, < ba2a5b66f1d414eb8403d655f8813783892cfc85 | ≥ e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9, < a386c83043015a703e227775f778e40343f45911 | ≥ e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9, < d535363299822c5caa543787b21bd5cfa3e41949 | ≥ e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9, < e8bb506e6ef749ac0336f3e579d8d02396b7d832 | 5.15

3 vendors · 160 products

References

13 links
Show all 13 references