CVE-2025-39941

Kernel-memory leak via concurrent slot writes

Published Oct 4, 2025 · Updated Oct 4, 2025

Race condition in the Linux zram driver allows local users to exhaust kernel memory by issuing concurrent writes to one slot. The write path frees the existing zsmalloc handle before compression, then installs a replacement under a separate slot-lock scope, allowing one concurrent replacement handle to be lost. Local low-privileged access and an active zram device are required; repeated races leak kernel allocations and can interrupt system availability.

CVSS severity4.7
Medium
EPSS probability0.10%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Race condition in the Linux zram driver allows local users to exhaust kernel memory by issuing concurrent writes to one slot. The write path frees the existing zsmalloc handle before compression, then installs a replacement under a separate slot-lock scope, allowing one concurrent replacement handle to be lost. Local low-privileged access and an active zram device are required; repeated races leak kernel allocations and can interrupt system availability.

The record

CVE
CVE-2025-39941
Published
Oct 4, 2025
Updated
Oct 4, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-362, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 4, 2025CVE publishedPublication date reported by the CVE source.
  2. Oct 4, 2025Record 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=6.14
  2. Affected versionversion=71268035f5d734ad6373d953298bd5779985497a <ce4be9e4307c5a60701ff6e0cafa74caffdc54ce
  3. Affected versionversion=71268035f5d734ad6373d953298bd5779985497a <ff750e9f2c4d63854c33967d1646b5e89a9a19a2

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=6.14; version=71268035f5d734ad6373d953298bd5779985497a <ce4be9e4307c5a60701ff6e0cafa74caffdc54ce; version=71268035f5d734ad6373d953298bd5779985497a <ff750e9f2c4d63854c33967d1646b5e89a9a19a2

Published CVSS scores

4.7NIST NVDCVSS:3.1/AV:L/AC:H/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 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-362Concurrent Execution using Shared Resource with Improper Synchronization ('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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