CVE-2020-36775

System hang via blocking compressed-write operation lock

Published Feb 26, 2024 · Updated May 11, 2026

Deadlock in F2FS compressed-page writes in Linux 5.6 allows local users to hang the system by writing a compression-enabled file. f2fs_write_compressed_pages acquires the operation lock after preparing its dnode instead of using f2fs_trylock_op first and returning EAGAIN when unavailable. Reachability requires local access to a compression-enabled F2FS filesystem, and the reported consequence is a system hang rather than data access or privilege escalation.

CVSS severity5.5
Medium
EPSS probability0.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Deadlock in F2FS compressed-page writes in Linux 5.6 allows local users to hang the system by writing a compression-enabled file. f2fs_write_compressed_pages acquires the operation lock after preparing its dnode instead of using f2fs_trylock_op first and returning EAGAIN when unavailable. Reachability requires local access to a compression-enabled F2FS filesystem, and the reported consequence is a system hang rather than data access or privilege escalation.

The record

CVE
CVE-2020-36775
Published
Feb 26, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-667, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 26, 2024CVE publishedPublication date reported by the CVE source.
  2. May 11, 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=4c8ff7095bef64fc47e996a938f7d57f9e077da3 <8e8542437bb4070423c9754d5ba270ffdbae8c8d
  2. Affected versionversion=4c8ff7095bef64fc47e996a938f7d57f9e077da3 <df77fbd8c5b222c680444801ffd20e8bbc90a56e
  3. Affected versionversion=5.6

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=4c8ff7095bef64fc47e996a938f7d57f9e077da3 <8e8542437bb4070423c9754d5ba270ffdbae8c8d; version=4c8ff7095bef64fc47e996a938f7d57f9e077da3 <df77fbd8c5b222c680444801ffd20e8bbc90a56e; version=5.6

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-667Improper Locking
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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