CVE-2025-21693: mm: zswap: properly synchronize freeing resources during CPU hotunplug

highCVSS 7.8CVE-2025-21693

CSIRTS triage

vendor: Linux product: zswap Denial of service

What: Improper synchronization of resource freeing during CPU hotunplug causes race conditions in zswap.
Who is affected: Linux systems with CPU hotplug capability using zswap memory compression.
Urgency: High priority; race condition can lead to memory corruption or system instability.
Action: Apply kernel patches synchronizing zswap resource cleanup during CPU hotplug events.

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

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Details

Source: Microsoft Security Response Center (INTL · vendor-psirt · site)
Severity: high — CVSS 7.8
Published: 2026-08-06
Exploitation: Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-21693

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-2025-216930.20% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 10% of all EPSS-scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2025-21693	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

high[UPDATE] [high] Linux Kernel: Multiple vulnerabilitiescert-bund

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