CVE-2025-38565 perf/core: Exit early on perf_mmap() fail

What is CVE-2025-38565?

CVE-2025-38565 is a high-severity denial of service vulnerability in Debian Debian Linux, published on 19 Aug 2025. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

In the Linux kernel, the following vulnerability has been resolved:

perf/core: Exit early on perf_mmap() fail

When perf_mmap() fails to allocate a buffer, it still invokes the event_mapped() callback of the related event. On X86 this might increase the perf_rdpmc_allowed reference counter. But nothing undoes this as perf_mmap_close() is never called in this case, which causes another reference count leak.

Return early on failure to prevent that.

Which versions are affected by CVE-2025-38565?

It affects 2 products.

Products include Debian Debian Linux, Linux kernel.

How do I fix CVE-2025-38565?

Apply the vendor's patch.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2025-38565 being exploited?

There is no known exploitation of CVE-2025-38565 in the wild and no public exploit code.

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All Debian Debian Linux vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as AZL-66539, AZL-73803, BELL-CVE-2025-38565, DEBIAN-CVE-2025-38565, GHSA-j97q-xq86-pq24, ROOT-OS-DEBIAN-11-CVE-2025-38565 and 4 more.