CVE-2026-80554: s390/vfio_ccw: Limit the number of channel program segments

mediumCVSS 5.5CVE-2026-80554

CSIRTS triage

vendor: Linux product: Linux Kernel Memory corruption

What: A use-after-free vulnerability exists in the Atmel MCI driver due to improper synchronization of removal operations with active requests.
Who is affected: Systems running Linux kernel with Atmel MCI mmc controller support enabled.
Urgency: Medium priority; CVSS 4.7 indicates moderate impact and should be patched in standard update cycles.
Action: Apply a Linux kernel update that fixes the race condition in atmci_remove.

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-2026-80554

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-2026-805540.14% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 4% of all EPSS-scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-80554	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 s390/vfio_ccw

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-2026-80555: In the Linux kernel, the following vulnerability has been resolved: s390/vfio_ccw: Free all me…nvd · 2026-08-26
criticalCVE-2026-80554: In the Linux kernel, the following vulnerability has been resolved: s390/vfio_ccw: Limit the n…nvd · 2026-08-26
highCVE-2026-80553: In the Linux kernel, the following vulnerability has been resolved: s390/vfio_ccw: Cancel exis…nvd · 2026-08-26
highCVE-2026-80552: In the Linux kernel, the following vulnerability has been resolved: s390/vfio_ccw: Ensure inde…nvd · 2026-08-26
criticalCVE-2026-80551: In the Linux kernel, the following vulnerability has been resolved: s390/vfio_ccw: Ensure firs…nvd · 2026-08-26
highCVE-2026-80550: In the Linux kernel, the following vulnerability has been resolved: s390/vfio_ccw: Fix out of …nvd · 2026-08-26