CVE-2026-80557: In the Linux kernel, the following vulnerability has been resolved: libceph: fix OOB read in decode_watchers(

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CRITICAL 9.8REMOTEWATCHLIST

CVE-2026-80557 is a critical-severity flaw (CVSS 9.8) affecting affected software. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

In the Linux kernel, the following vulnerability has been resolved: libceph: fix OOB read in decode_watchers() via missing bounds check ceph_start_decoding() validates that struct_len bytes remain in the buffer after the encoding header, but accepts struct_len=0 as valid: ceph_decode_need(p, end, 0, bad) always passes. When a malicious or compromised OSD sends an obj_list_watch_response_t reply with struct_len=0, ceph_start_decoding() returns s

Why this priority

Critical severity
CISA SSVC: automatable with total technical impact
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.5% (top 56%)
CISA exploited list	No
Published	2026-08-26
Last modified	2026-10-16

Publisher (CNA): kernel.org

Last updated 2026-10-16 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Timeline

2026-08-26 15:17 UTCPublished CVE record published
2026-10-16 20:18 UTCUpdated Record last modified

Exact fixes by distribution

Fedora 46 · rubygem-mechanize · FIXED · 2.14.2-1.fc46 · FEDORA-2026-d2e3b5fc5d · source

sudo dnf upgrade --advisory=FEDORA-2026-d2e3b5fc5d

Fedora ELN · opkssh · FIXED · 0.19.1-1.eln159 · FEDORA-2026-45a9706969 · source

sudo dnf upgrade --advisory=FEDORA-2026-45a9706969

Ubuntu 22.04 · linux · NO FIX YET

Ubuntu 20.04 · linux · NO FIX YET

Ubuntu 24.04 · linux · NO FIX YET

Ubuntu 20.04 · linux-hwe-5.15 · NO FIX YET

Ubuntu 22.04 · linux-hwe-6.8 · NO FIX YET

Debian 12 · linux · FIXED · 6.1.187-1

sudo apt update && sudo apt install --only-upgrade linux dpkg --compare-versions "$(dpkg-query -W -f='${Version}' linux)" ge "6.1.187-1" && echo PATCHED || echo STILL-VULNERABLE

Debian 13 · linux · FIXED · 6.12.107-1

sudo apt update && sudo apt install --only-upgrade linux dpkg --compare-versions "$(dpkg-query -W -f='${Version}' linux)" ge "6.12.107-1" && echo PATCHED || echo STILL-VULNERABLE

Debian 12 · linux-6.12 · FIXED · 6.12.107-1~deb12u1

sudo apt update && sudo apt install --only-upgrade linux-6.12 dpkg --compare-versions "$(dpkg-query -W -f='${Version}' linux-6.12)" ge "6.12.107-1~deb12u1" && echo PATCHED || echo STILL-VULNERABLE

RHEL 10 · kernel · DEFERRED

RHEL 6 · kernel · NOT AFFECTED

RHEL 7 · kernel · DEFERRED

RHEL 7 · kernel-rt · DEFERRED

RHEL 8 · kernel · DEFERRED

Amazon Linux 2023 · see advisory · FIXED · ALAS2023-2026-3196 · source

sudo dnf update --advisory=ALAS2023-2026-3196

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-80557?

No fixed release is listed yet. Watch the vendor advisory and apply any mitigation shown on this page.

Is CVE-2026-80557 being exploited?

CVE-2026-80557 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-80557 affect?

CVE-2026-80557 affects affected software. Severity is critical (CVSS 9.8). In the Linux kernel, the following vulnerability has been resolved: libceph: fix OOB read in decode_watchers() via missing bounds check ceph_start_decoding() validates that struct_len bytes remain in the buffer after the encoding header,

How urgent is CVE-2026-80557?

Priority 58/100. Critical severity; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Linux kernel vulnerabilities · Ceph vulnerabilities

References

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