CVE-2024-56558

Kernel warning via NFSD export refcount race

Published Dec 27, 2024 · Updated Aug 5, 2026

Use-after-free in the NFSD component of Linux allows local users to trigger a kernel warning through export-cache inspection. The e_show function relies only on RCU while displaying an NFSD export, so the export reference count can reach zero before exp_get increments it. Reaching the warning requires local access to read the export-cache interface during the lifetime race; the published trace demonstrates a refcount use-after-free warning, not code execution.

CVSS severity7.8
High
EPSS probability0.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in the NFSD component of Linux allows local users to trigger a kernel warning through export-cache inspection. The e_show function relies only on RCU while displaying an NFSD export, so the export reference count can reach zero before exp_get increments it. Reaching the warning requires local access to read the export-cache interface during the lifetime race; the published trace demonstrates a refcount use-after-free warning, not code execution.

The record

CVE
CVE-2024-56558
Published
Dec 27, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-416, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Dec 27, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 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=3.17
  2. Affected versionversion=bf18f163e89c52e09c96534db45c4274273a0b34 <1cecfdbc6bfc89c516d286884c7f29267b95de2b
  3. Affected versionversion=bf18f163e89c52e09c96534db45c4274273a0b34 <6cefcadd34e3c71c81ea64b899a0daa86314a51a
  4. Affected versionversion=bf18f163e89c52e09c96534db45c4274273a0b34 <7365d1f8de63cffdbbaa2287ce0205438e1a922f
  5. Affected versionversion=bf18f163e89c52e09c96534db45c4274273a0b34 <7d8f7816bebcd2e7400bb4d786eccb8f33c9f9ec
  6. Affected versionversion=bf18f163e89c52e09c96534db45c4274273a0b34 <7fd29d284b55c2274f7a748e6c5f25b4758b8da5
  7. Affected versionversion=bf18f163e89c52e09c96534db45c4274273a0b34 <be8f982c369c965faffa198b46060f8853e0f1f0
  8. Affected versionversion=bf18f163e89c52e09c96534db45c4274273a0b34 <e2fa0d0e327279a8defb87b263cd0bf288fd9261

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=3.17; version=bf18f163e89c52e09c96534db45c4274273a0b34 <1cecfdbc6bfc89c516d286884c7f29267b95de2b; version=bf18f163e89c52e09c96534db45c4274273a0b34 <6cefcadd34e3c71c81ea64b899a0daa86314a51a; version=bf18f163e89c52e09c96534db45c4274273a0b34 <7365d1f8de63cffdbbaa2287ce0205438e1a922f; version=bf18f163e89c52e09c96534db45c4274273a0b34 <7d8f7816bebcd2e7400bb4d786eccb8f33c9f9ec; version=bf18f163e89c52e09c96534db45c4274273a0b34 <7fd29d284b55c2274f7a748e6c5f25b4758b8da5; version=bf18f163e89c52e09c96534db45c4274273a0b34 <be8f982c369c965faffa198b46060f8853e0f1f0; version=bf18f163e89c52e09c96534db45c4274273a0b34 <e2fa0d0e327279a8defb87b263cd0bf288fd9261

Published CVSS scores

7.1OracleCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
7.8CanonicalCVSS:3.1/AV:L/AC:L/PR:L/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free
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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