Improper Update of Reference Count The advisory has been revoked - it doesn't affect any version of package libperf (opens in a new tab)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-CENTOS10-LIBPERF-15708835
- published20 Mar 2026
- disclosed18 Mar 2026
Introduced: 18 Mar 2026
CVE-2026-23248 (opens in a new tab)Amendment
The Centos security team deemed this advisory irrelevant for Centos:10.
NVD Description
Note: Versions mentioned in the description apply only to the upstream libperf package and not the libperf package as distributed by Centos.
In the Linux kernel, the following vulnerability has been resolved:
perf/core: Fix refcount bug and potential UAF in perf_mmap
Syzkaller reported a refcount_t: addition on 0; use-after-free warning in perf_mmap.
The issue is caused by a race condition between a failing mmap() setup and a concurrent mmap() on a dependent event (e.g., using output redirection).
In perf_mmap(), the ring_buffer (rb) is allocated and assigned to event->rb with the mmap_mutex held. The mutex is then released to perform map_range().
If map_range() fails, perf_mmap_close() is called to clean up. However, since the mutex was dropped, another thread attaching to this event (via inherited events or output redirection) can acquire the mutex, observe the valid event->rb pointer, and attempt to increment its reference count. If the cleanup path has already dropped the reference count to zero, this results in a use-after-free or refcount saturation warning.
Fix this by extending the scope of mmap_mutex to cover the map_range() call. This ensures that the ring buffer initialization and mapping (or cleanup on failure) happens atomically effectively, preventing other threads from accessing a half-initialized or dying ring buffer.
References
- https://bugzilla.redhat.com/show_bug.cgi?id=2448596
- https://access.redhat.com/security/cve/CVE-2026-23248
- https://git.kernel.org/stable/c/77de62ad3de3967818c3dbe656b7336ebee461d2
- https://git.kernel.org/stable/c/ac7ecb65af170a7fc193e7bd8be15dac84ec6a56
- https://git.kernel.org/stable/c/c27dea9f50ed525facb62ef647dddc4722456e07