CVE-2026-80557Network attack vectorHinoki check available

Kernel denial of service via unchecked watcher count

Published Aug 26, 2026 · Updated Aug 27, 2026

Out-of-bounds read in Linux kernel 4.9 through 7.1.9 allows remote attackers controlling a Ceph OSD to crash or stall kernel clients. In decode_watchers(), ceph_start_decoding() accepts a zero-length structure, then ceph_decode_32() reads four bytes beyond the validated reply and passes the value to kzalloc_objs() as the watcher count. Reachability requires a malicious or compromised OSD session and a kernel client operation that lists watchers; consequences include kernel memory corruption, a crash, OOM, or an RBD worker stall.

CVSS severity9.8
Critical
EPSS probability0.52%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Out-of-bounds read in Linux kernel 4.9 through 7.1.9 allows remote attackers controlling a Ceph OSD to crash or stall kernel clients. In decode_watchers(), ceph_start_decoding() accepts a zero-length structure, then ceph_decode_32() reads four bytes beyond the validated reply and passes the value to kzalloc_objs() as the watcher count. Reachability requires a malicious or compromised OSD session and a kernel client operation that lists watchers; consequences include kernel memory corruption, a crash, OOM, or an RBD worker stall.

The record

CVE
CVE-2026-80557
Published
Aug 26, 2026
Updated
Aug 27, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-125, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 26, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 27, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=4.9
  2. Affected versionversion=a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c <00ead17c7de137a692edee59f2772e6af687e8eb
  3. Affected versionversion=a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c <1c824e7c75bb4adf19553dd4ea944a5d83096be8
  4. Affected versionversion=a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c <7130d94846dadbb97b6b7f4d78a3a7bba6e3daa1
  5. Affected versionversion=a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c <85479b7d65b4ebcb07fbbe57230976793974ab4a
  6. Affected versionversion=a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c <c59219a6b62d74936963983e5815524c3de8dd79
  7. Affected versionversion=a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c <cb8246e5846dbbe34930903a90c7a90dd8e5910b
  8. Affected versionversion=a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c <eab3eeb68bfc639d74f27256f05546af5c4f787d
  9. Affected versionversion=a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c <f161be39201eb5f9b1f58fb8f90b8a9cd3931eb6

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=4.9; version=a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c <00ead17c7de137a692edee59f2772e6af687e8eb; version=a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c <1c824e7c75bb4adf19553dd4ea944a5d83096be8; version=a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c <7130d94846dadbb97b6b7f4d78a3a7bba6e3daa1; version=a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c <85479b7d65b4ebcb07fbbe57230976793974ab4a; version=a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c <c59219a6b62d74936963983e5815524c3de8dd79; version=a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c <cb8246e5846dbbe34930903a90c7a90dd8e5910b; version=a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c <eab3eeb68bfc639d74f27256f05546af5c4f787d; version=a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c <f161be39201eb5f9b1f58fb8f90b8a9cd3931eb6

Published CVSS scores

9.8Linux Kernel CVE TeamCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-125Out-of-bounds Read
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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