CVE-2026-80631: btrfs: lzo: reject compressed segment that overflows the compressed input

mediumCVSS 5.5CVE-2026-80631

CSIRTS triage

vendor: Linux product: Linux kernel Memory corruption

What: The btrfs lzo compression handler does not reject compressed segments that overflow the compressed input buffer.
Who is affected: Systems running Linux kernel with btrfs filesystem and lzo compression enabled.
Urgency: Medium priority; not currently exploited but memory corruption can lead to data loss or kernel instability.
Action: Apply kernel security patch when available or disable lzo compression on btrfs filesystems.

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: medium — CVSS 5.5
Published: 2026-08-11
Exploitation: Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-80631

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-2026-806310.34% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 27% of all EPSS-scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-80631	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

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

Recent advisories for btrfs

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-2026-80631: In the Linux kernel, the following vulnerability has been resolved: btrfs: lzo: reject compres…nvd · 2026-08-28
criticalCVE-2026-74723: In the Linux kernel, the following vulnerability has been resolved: btrfs: lzo: reject inline …nvd · 2026-08-22
unknownCVE-2026-74722: In the Linux kernel, the following vulnerability has been resolved: btrfs: fix memory leak in …nvd · 2026-08-22
highCVE-2026-74572: In the Linux kernel, the following vulnerability has been resolved: btrfs: zoned: fix deadlock…nvd · 2026-08-15
unknownCVE-2026-74571: In the Linux kernel, the following vulnerability has been resolved: btrfs: skip global block r…nvd · 2026-08-15
highCVE-2026-74321: In the Linux kernel, the following vulnerability has been resolved: btrfs: fix invalid pointer…nvd · 2026-08-15