CVE-2026-80527Network attack vector

Reader-thread denial of service via stale capability state

Published Aug 26, 2026 · Updated Aug 27, 2026

Denial of service in the Linux kernel CephFS client from 5.8 allows remote attackers to hang reader threads through capability revocation. __prep_cap updates mds_wanted before the capability request is queued, so __ceph_get_caps trusts stale state and waits indefinitely for FILE_RD. Exploitation requires write access from another client to the shared CephFS file and a subsequent read on the affected host; the consequence is stalled CephFS-backed work.

CVSS severity7.5
High
EPSS probability0.51%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in the Linux kernel CephFS client from 5.8 allows remote attackers to hang reader threads through capability revocation. __prep_cap updates mds_wanted before the capability request is queued, so __ceph_get_caps trusts stale state and waits indefinitely for FILE_RD. Exploitation requires write access from another client to the shared CephFS file and a subsequent read on the affected host; the consequence is stalled CephFS-backed work.

The record

CVE
CVE-2026-80527
Published
Aug 26, 2026
Updated
Aug 27, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-367, 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=0a454bdd501ad1aa30bb72e9581efa338ad6ce5c <50958bb928bad3bdba9e5d1b7ff4bbadcf6951e6
  2. Affected versionversion=0a454bdd501ad1aa30bb72e9581efa338ad6ce5c <5e84bc6f67e19fdd192d8b215de728acbfc12572
  3. Affected versionversion=0a454bdd501ad1aa30bb72e9581efa338ad6ce5c <5fedf279a1ea369d39c8b06dd4547cdc576065d0
  4. Affected versionversion=0a454bdd501ad1aa30bb72e9581efa338ad6ce5c <9e55fe24c548ad3163903eb58bb002d28d32a630
  5. Affected versionversion=0a454bdd501ad1aa30bb72e9581efa338ad6ce5c <a3bc6b3e9ef3f5f5cb85a902a30a090c7931127c
  6. Affected versionversion=0a454bdd501ad1aa30bb72e9581efa338ad6ce5c <b5661524c5a45085a866864ca9b8ae2513dfd67a
  7. Affected versionversion=0a454bdd501ad1aa30bb72e9581efa338ad6ce5c <e05c315b4da0c16ea800ee4b2cb6c617f586d1b5
  8. Affected versionversion=0a454bdd501ad1aa30bb72e9581efa338ad6ce5c <fcce1b3be6d286aa80831e730289f4c062053ae6
  9. Affected versionversion=5.8

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=0a454bdd501ad1aa30bb72e9581efa338ad6ce5c <50958bb928bad3bdba9e5d1b7ff4bbadcf6951e6; version=0a454bdd501ad1aa30bb72e9581efa338ad6ce5c <5e84bc6f67e19fdd192d8b215de728acbfc12572; version=0a454bdd501ad1aa30bb72e9581efa338ad6ce5c <5fedf279a1ea369d39c8b06dd4547cdc576065d0; version=0a454bdd501ad1aa30bb72e9581efa338ad6ce5c <9e55fe24c548ad3163903eb58bb002d28d32a630; version=0a454bdd501ad1aa30bb72e9581efa338ad6ce5c <a3bc6b3e9ef3f5f5cb85a902a30a090c7931127c; version=0a454bdd501ad1aa30bb72e9581efa338ad6ce5c <b5661524c5a45085a866864ca9b8ae2513dfd67a; version=0a454bdd501ad1aa30bb72e9581efa338ad6ce5c <e05c315b4da0c16ea800ee4b2cb6c617f586d1b5; version=0a454bdd501ad1aa30bb72e9581efa338ad6ce5c <fcce1b3be6d286aa80831e730289f4c062053ae6; version=5.8

Published CVSS scores

5.5Red HatCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
7.5Linux kernel CVE teamCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-367Time-of-check Time-of-use (TOCTOU) Race Condition
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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