CVE-2025-21964

Service interruption via pre-validation acregmax conversion

Published Apr 1, 2025 · Updated May 11, 2026

Integer overflow in the Linux kernel CIFS client in affected releases beginning with 5.12 allows local users to interrupt service via acregmax. smb3_fs_context_parse_param multiplies the untrusted u32 seconds value by HZ before checking it against CIFS_MAX_ACTIMEO, so overflow can bypass the upper bound. A low-privileged local user able to supply CIFS mount parameters can cause a system hang or repeatable crash; no confidentiality or integrity impact is reported.

CVSS severity5.5
Medium
EPSS probability0.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Integer overflow in the Linux kernel CIFS client in affected releases beginning with 5.12 allows local users to interrupt service via acregmax. smb3_fs_context_parse_param multiplies the untrusted u32 seconds value by HZ before checking it against CIFS_MAX_ACTIMEO, so overflow can bypass the upper bound. A low-privileged local user able to supply CIFS mount parameters can cause a system hang or repeatable crash; no confidentiality or integrity impact is reported.

The record

CVE
CVE-2025-21964
Published
Apr 1, 2025
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-190, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 1, 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

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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=5.12
  2. Affected versionversion=5780464614f6abe6026f00cf5a0777aa453ba450 <0252c33cc943e9e48ddfafaa6b1eb72adb68a099
  3. Affected versionversion=5780464614f6abe6026f00cf5a0777aa453ba450 <5f500874ab9b3cc8c169c2ab49f00b838520b9c5
  4. Affected versionversion=5780464614f6abe6026f00cf5a0777aa453ba450 <7489161b1852390b4413d57f2457cd40b34da6cc
  5. Affected versionversion=5780464614f6abe6026f00cf5a0777aa453ba450 <833f2903eb8b70faca7967319e580e9ce69729fc
  6. Affected versionversion=5780464614f6abe6026f00cf5a0777aa453ba450 <a13351624a6af8d91398860b8c9d4cf6c8e63de5
  7. Affected versionversion=5780464614f6abe6026f00cf5a0777aa453ba450 <dd190168e60ac15408f074a1fe0ce36aff34027b

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.12; version=5780464614f6abe6026f00cf5a0777aa453ba450 <0252c33cc943e9e48ddfafaa6b1eb72adb68a099; version=5780464614f6abe6026f00cf5a0777aa453ba450 <5f500874ab9b3cc8c169c2ab49f00b838520b9c5; version=5780464614f6abe6026f00cf5a0777aa453ba450 <7489161b1852390b4413d57f2457cd40b34da6cc; version=5780464614f6abe6026f00cf5a0777aa453ba450 <833f2903eb8b70faca7967319e580e9ce69729fc; version=5780464614f6abe6026f00cf5a0777aa453ba450 <a13351624a6af8d91398860b8c9d4cf6c8e63de5; version=5780464614f6abe6026f00cf5a0777aa453ba450 <dd190168e60ac15408f074a1fe0ce36aff34027b

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.

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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-190Integer Overflow or Wraparound
T1499.004Application or System Exploitation

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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