CVE-2025-37878: perf/core: Fix WARN_ON(!ctx) in __free_event() for partial init

mediumCVSS 5.5CVE-2025-37878

CSIRTS triage

vendor: Linux product: Linux Kernel Denial of service

What: A WARN_ON assertion in __free_event() during partial event initialization can cause kernel warnings or system instability.
Who is affected: Systems with perf event tracking enabled under certain initialization failure conditions.
Urgency: Medium priority; can trigger kernel warnings and potential hangs during error paths in perf initialization.
Action: Apply kernel patches addressing CVE-2025-37878 to handle partial event initialization safely.

AI-assisted analysis generated from the source advisory — verify against the original.

⚡ Watch Linux Kernel

Get an email when a new Linux Kernel advisory drops — max one per day, one-click unsubscribe.

Details

Source: Microsoft Security Response Center (INTL · vendor-psirt · site)
Severity: medium — CVSS 5.5
Published: 2026-08-06
Exploitation: Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-37878

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2025-378780.26% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 17% of all EPSS-scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2025-37878	coverage & exploitation status	NVD · CVE.org

Recent advisories for perf/core

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

highCVE-2026-74637: In the Linux kernel, the following vulnerability has been resolved: perf/core: Fix group leade…nvd · 2026-08-22
mediumCVE-2026-74637: perf/core: Fix group leader use-after-free after sibling detachmsrc · 2026-08-11
highCVE-2026-64556: perf/core: Detach event groups during remove_on_execmsrc · 2026-08-06
highCVE-2026-64556: In the Linux kernel, the following vulnerability has been resolved: perf/core: Detach event gr…nvd · 2026-07-29