CVE-2025-40268

Local memory exhaustion via repeated CIFS source parsing

Published Dec 6, 2025 · Updated May 11, 2026

Memory leak in the Linux CIFS client from 5.11 allows local users to exhaust kernel memory through repeated fsconfig source parameters. smb3_fs_context_parse_param replaces ctx->source or fc->source without releasing the prior allocation, so a second source parse leaves the first object unreachable. Reaching the flaw requires local access to create and configure a CIFS filesystem context; repeated triggers consume kernel memory and can degrade availability.

CVSS severity3.3
Low
EPSS probability0.19%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Memory leak in the Linux CIFS client from 5.11 allows local users to exhaust kernel memory through repeated fsconfig source parameters. smb3_fs_context_parse_param replaces ctx->source or fc->source without releasing the prior allocation, so a second source parse leaves the first object unreachable. Reaching the flaw requires local access to create and configure a CIFS filesystem context; repeated triggers consume kernel memory and can degrade availability.

The record

CVE
CVE-2025-40268
Published
Dec 6, 2025
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.001
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Dec 6, 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=5.11
  2. Affected versionversion=af1a3d2ba9543e99d78914d8fb88b61d0531d9a1 <4515743cc7a42e1d67468402a6420c195532a6fa
  3. Affected versionversion=af1a3d2ba9543e99d78914d8fb88b61d0531d9a1 <48c17341577e25a22feb13d694374b61d974edbc
  4. Affected versionversion=af1a3d2ba9543e99d78914d8fb88b61d0531d9a1 <868fc62811d3fabcf5685e14f36377a855d5412d
  5. Affected versionversion=af1a3d2ba9543e99d78914d8fb88b61d0531d9a1 <e8c73eb7db0a498cd4b22d2819e6ab1a6f506bd6

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.11; version=af1a3d2ba9543e99d78914d8fb88b61d0531d9a1 <4515743cc7a42e1d67468402a6420c195532a6fa; version=af1a3d2ba9543e99d78914d8fb88b61d0531d9a1 <48c17341577e25a22feb13d694374b61d974edbc; version=af1a3d2ba9543e99d78914d8fb88b61d0531d9a1 <868fc62811d3fabcf5685e14f36377a855d5412d; version=af1a3d2ba9543e99d78914d8fb88b61d0531d9a1 <e8c73eb7db0a498cd4b22d2819e6ab1a6f506bd6

Published CVSS scores

3.3Amazon LinuxCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

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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

T1499.001OS Exhaustion Flood

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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