CVE-2025-38244Network attack vector

System hang via inverted SMB reconnect locks

Published Jul 9, 2025 · Updated Aug 5, 2026

Improper locking in the Linux SMB client allows remote attackers to hang the system through a crafted SMB response. The cifs_signal_cifsd_for_reconnect function acquires chan_lock before srv_lock, reversing the established srv_lock-to-ses_lock-to-chan_lock order and creating a circular dependency. An already-mounted SMB share connected to a malicious or on-path-controlled server is sufficient; the deadlock provides no data-read or data-write capability.

CVSS severity7.5
High
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper locking in the Linux SMB client allows remote attackers to hang the system through a crafted SMB response. The cifs_signal_cifsd_for_reconnect function acquires chan_lock before srv_lock, reversing the established srv_lock-to-ses_lock-to-chan_lock order and creating a circular dependency. An already-mounted SMB share connected to a malicious or on-path-controlled server is sufficient; the deadlock provides no data-read or data-write capability.

The record

CVE
CVE-2025-38244
Published
Jul 9, 2025
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 9, 2025CVE 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

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=6.0
  2. Affected versionversion=d7d7a66aacd6fd8ca57baf08a7bac5421282f6f8 <711741f94ac3cf9f4e3aa73aa171e76d188c0819
  3. Affected versionversion=d7d7a66aacd6fd8ca57baf08a7bac5421282f6f8 <7f3ead8ebc0ef65b6c89a13912b4e80218425629
  4. Affected versionversion=d7d7a66aacd6fd8ca57baf08a7bac5421282f6f8 <c82c7041258d96e3286f6790ab700e4edd3cc9e3
  5. Affected versionversion=d7d7a66aacd6fd8ca57baf08a7bac5421282f6f8 <fe035dc78aa6ca8f862857d45beaf7a0e03206ca

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=6.0; version=d7d7a66aacd6fd8ca57baf08a7bac5421282f6f8 <711741f94ac3cf9f4e3aa73aa171e76d188c0819; version=d7d7a66aacd6fd8ca57baf08a7bac5421282f6f8 <7f3ead8ebc0ef65b6c89a13912b4e80218425629; version=d7d7a66aacd6fd8ca57baf08a7bac5421282f6f8 <c82c7041258d96e3286f6790ab700e4edd3cc9e3; version=d7d7a66aacd6fd8ca57baf08a7bac5421282f6f8 <fe035dc78aa6ca8f862857d45beaf7a0e03206ca

Published CVSS scores

5.5Canonical UbuntuCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
7.5LinuxCVSS:3.1/AV:N/AC:L/PR:N/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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

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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