9.8

CVE-2026-43376: ksmbd: fix use-after-free by using call_rcu() for oplock_info

Analyzed
AliasesUBUNTU-CVE-2026-43376DEBIAN-CVE-2026-43376
Published 08-05-2026Last modified 05-08-2026

Vulnerability summary

CVE-2026-43376 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 38.7% 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 2 · Related 8
USN-8604-1USN-8605-1USN-8490-1USN-8490-2USN-8491-1USN-8508-1

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 by using call_rcu() for oplock_info ksmbd currently frees oplock_info immediately using kfree(), even though it is accessed under RCU read-side critical sections in places like opinfo_get() and proc_show_files(). Since there is no RCU grace period delay between nullifying the pointer and freeing the memory, a reader can still access oplock_info structure after it has been freed. This can leads to a use-after-free especially in opinfo_get() where atomic_inc_not_zero() is called on already freed memory. Fix this by switching to deferred freeing using call_rcu().

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.

Ubuntu107 products
  • linux< 6.17.0-40.40
  • linux-allwinner-5.19All versions (No fix recorded)
  • linux-aws< 6.17.0-1019.19
  • linux-aws-5.0All versions (No fix recorded)
  • linux-aws-5.11All versions (No fix recorded)
Linux2 products
  • linux≥ 296cb5457cc6f4a754c4ae29855f8a253d52bcc6, < 302fef75512b2c8329a3f5efab1ae7ba2562387a | ≥ d54ab1520d43e95f9b2e22d7a05fc9614192e5a5, < 08aa9f3c8cf4d0bee44df540dfe34e8d64069f2c | ≥ 18b4fac5ef17f77fed9417d22210ceafd6525fc7, < 1d6abf145615dbfe267ce3b0a271f95e3780e18e | ≥ 18b4fac5ef17f77fed9417d22210ceafd6525fc7, < ce8507ee82c888126d8e7565e27c016308d24cde | ≥ 18b4fac5ef17f77fed9417d22210ceafd6525fc7, < 1dfd062caa165ec9d7ee0823087930f3ab8a6294 | d73686367ad68534257cd88a36ca3c52cb8b81d8 | ≥ 6.6.88, < 6.6.130 | ≥ 6.12.25, < 6.12.78 | ≥ 6.14.4, < 6.15 | 6.15
  • linux_kernelEOL≥ 6.6.88, < 6.6.130 | ≥ 6.12.25, < 6.12.78 | ≥ 6.14.4, < 6.15 | ≥ 6.15.1, < 6.18.19 | ≥ 6.19, < 6.19.9 | 6.15 | 6.15:rc3 | 6.15:rc4 | 6.15:rc5 | 6.15:rc6 | 6.15:rc7 | 7.0:rc1 | 7.0:rc2 | 7.0:rc3
Debian1 product
  • linux< 6.12.85-1 | < 6.19.10-1

3 vendors · 110 products

References

17 links
Show all 17 references