Vulnerability in Linux
CVE-2026-23380
In the Linux kernel, the following vulnerability has been resolved: tracing: Fix WARN_ON in tracing_buffers_mmap_close When a process forks, the child process copies the parent's VMAs but the user_mapped reference count is not incremented. As a result, when both the parent and child processes exit, tracing_buffers_mmap_close() is called twice. On the second call, user_mapped is already 0, causing the function to return -ENODEV and triggering a WARN_ON. Normally, this isn't an issue as the memory is mapped with VM_DONTCOPY set. But this is only a hint, and the application can call madvise(MADVISE_DOFORK) which resets the VM_DONTCOPY flag. When the application does that, it can trigger this issue on fork. Fix it by incrementing the user_mapped reference count without re-mapping the pages in the VMA's open callback.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.5 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.001 (1.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 1st percentile — 1.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.001 · newest: 0.001 · change: 0.000
Affected products
- Linux — versions cf9f0f7c4c5bb45e7bb270e48bab6f7837825a64, 6.10, 0
- Linux Kernel — versions 6.10, 7.0
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-23380?
- CVE-2026-23380 is a medium-severity vulnerability in Linux, classified under Reachable Assertion. CVSS score: 5.5/10. Published 2026-03-25.
- How severe is CVE-2026-23380?
- Medium severity. CVSS v3 base score is 5.5 out of 10.