CVE-2022-49704

Kernel resource exhaustion via leaked 9p fid references

Published Feb 26, 2025 · Updated May 11, 2026

Reference-count leakage in the Linux 9p client allows local users to exhaust kernel resources through legacy-protocol symlink access. v9fs_vfs_get_link calls v9fs_fid_lookup before rejecting sessions without 9p2000.u support, then returns without clunking the acquired fid. A local user must access a symlink on a mounted legacy 9p filesystem; repeated requests consume references until service availability is lost.

CVSS severity5.5
Medium
EPSS probability0.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reference-count leakage in the Linux 9p client allows local users to exhaust kernel resources through legacy-protocol symlink access. v9fs_vfs_get_link calls v9fs_fid_lookup before rejecting sessions without 9p2000.u support, then returns without clunking the acquired fid. A local user must access a symlink on a mounted legacy 9p filesystem; repeated requests consume references until service availability is lost.

The record

CVE
CVE-2022-49704
Published
Feb 26, 2025
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 26, 2025CVE 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

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=5.11
  2. Affected versionversion=6636b6dcc3db2258cd0585b8078c1c225c4b6dde <e5690f263208c5abce7451370b7786eb25b405eb
  3. Affected versionversion=6636b6dcc3db2258cd0585b8078c1c225c4b6dde <e7b6d622bd812013eb39c8f4cd65b7ee8ede1e02
  4. Affected versionversion=6636b6dcc3db2258cd0585b8078c1c225c4b6dde <f0126bcaee81dabc1926012126aa74caa03a4c6e

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.11; version=6636b6dcc3db2258cd0585b8078c1c225c4b6dde <e5690f263208c5abce7451370b7786eb25b405eb; version=6636b6dcc3db2258cd0585b8078c1c225c4b6dde <e7b6d622bd812013eb39c8f4cd65b7ee8ede1e02; version=6636b6dcc3db2258cd0585b8078c1c225c4b6dde <f0126bcaee81dabc1926012126aa74caa03a4c6e

Published CVSS scores

5.5CISA-ADPCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
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

T1499.004Application or System Exploitation

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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