9.8

CVE-2026-43379: ksmbd: fix use-after-free in smb_lazy_parent_lease_break_close()

Analyzed
AliasesUBUNTU-CVE-2026-43379DEBIAN-CVE-2026-43379
Published 08-05-2026Last modified 05-08-2026

Vulnerability summary

CVE-2026-43379 is a critical (CVSS 9.8) Use After Free vulnerability in linux. EPSS estimates a 0.44% chance of exploitation in the next 30 days, higher than 38.6% of scored vulnerabilities.

Priority
Prioritisesevere

Severe, CVSS 9.8 (CVE.org); no exploitation reported by the 5 checked sources; EPSS 0% (FIRST, 03-11-2026)

Source freshness unavailable

How is this decided?
CVSS score
9.8/10
010
Critical · v3.1 (CVE.org)
EPSS score
0.44%
0%100%
Low · -0.21 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 3
USN-8636-1USN-8636-2USN-8669-1

Timeline

  1. 08-05-2026
    PublishedVulnerability first disclosed.
  2. 05-08-2026
    Last modifiedVulnerability information updated.

Description

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix use-after-free in smb_lazy_parent_lease_break_close() opinfo pointer obtained via rcu_dereference(fp->f_opinfo) is being accessed after rcu_read_unlock() has been called. This creates a race condition where the memory could be freed by a concurrent writer between the unlock and the subsequent pointer dereferences (opinfo->is_lease, etc.), leading to a use-after-free.

CVSS metrics

5 scores · 4 sources · 2 versions

EPSS trend

Probability

0.44%

Chance of exploitation in the next 30 days

Percentile

39%

Versus all other CVEs

30-day change

Decrease -0.21 pp

From 0.65% on 04-10-2026

04-10-202603-11-2026

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

Affected systems

Version check

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

Ubuntu147 products
  • linuxAll versions (No fix recorded)
  • linux-allwinner-5.19All versions (No fix recorded)
  • linux-awsAll versions (No fix recorded)
  • linux-aws-5.0All versions (No fix recorded)
  • linux-aws-5.11All versions (No fix recorded)
Linux2 products
  • linux≥ 27b40b7bfcd121fe13a150ffe11957630cf49246, < bf4d66d72e4a9e268c1012c331ce9eaedb5e2086 | ≥ 5fb282ba4fef8985a5acf2b32681f2ec07732561, < 960699317d39f46611f4ebeb69edc567c1f4e6b6 | ≥ 5fb282ba4fef8985a5acf2b32681f2ec07732561, < dbbd328cf58261ca239756fe1c0d10c9518d3399 | ≥ 5fb282ba4fef8985a5acf2b32681f2ec07732561, < b3568347c51c46e2cabc356bc34676df98296619 | ≥ 5fb282ba4fef8985a5acf2b32681f2ec07732561, < eac3361e3d5dd8067b3258c69615888eb45e9f25 | ≥ 6.6.32, < 6.6.130 | 6.9
  • linux_kernel≥ 6.6.32, < 6.6.130 | ≥ 6.9, < 6.12.78 | ≥ 6.13, < 6.18.19 | ≥ 6.19, < 6.19.9 | 7.0:rc1 | 7.0:rc2 | 7.0:rc3
Debian1 product
  • linux< 6.12.85-1 | < 6.19.10-1

3 vendors · 150 products

References

12 links
Show all 12 references