CVE-2026-52956: libceph: Fix potential out-of-bounds access in __ceph_x_decrypt()

criticalCVSS 9.8CVE-2026-52956

CSIRTS triage

vendor: Linux product: libcephOther

What: There is a critical out-of-bounds access vulnerability in the __ceph_x_decrypt function.
Who is affected: Deployments using the libceph library.
Urgency: Remediation is very urgent due to the critical severity and high CVSS score, with no current exploitation reported.
Action: Update to the latest version of libceph that resolves this vulnerability.

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: critical — CVSS 9.8
Published: 2026-06-09
Exploitation: Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-52956

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-2026-529560.36% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 28% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-52956	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

Recent advisories for libceph

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-2026-52957: libceph: Fix potential null-ptr-deref in decode_choose_args()msrc · 2026-06-09
mediumCVE-2026-52954: libceph: handle rbtree insertion error in decode_choose_args()msrc · 2026-06-09
highCVE-2026-52955: libceph: Fix potential out-of-bounds access in crush_decode()msrc · 2026-06-09
mediumCVE-2026-52958: libceph: Fix potential out-of-bounds access in osdmap_decode()msrc · 2026-06-09