CVE-2025-39852

Service interruption via leaked TCP-AO child sockets

Published Sep 19, 2025 · Updated Sep 19, 2025

Memory leak in the Linux kernel allows local users to interrupt service by triggering a TCP-AO key-copy failure during IPv6 connection setup. The tcp_v6_syn_recv_sock error path returns after tcp_ao_copy_all_matching fails without calling inet_csk_prepare_forced_close and tcp_done, leaving the cloned child socket allocated. Reachability requires local low-privileged access and a TCP-AO-enabled socket path; repeated failures consume kernel memory and can deny service.

CVSS severity5.5
Medium
EPSS probability0.14%
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 kernel allows local users to interrupt service by triggering a TCP-AO key-copy failure during IPv6 connection setup. The tcp_v6_syn_recv_sock error path returns after tcp_ao_copy_all_matching fails without calling inet_csk_prepare_forced_close and tcp_done, leaving the cloned child socket allocated. Reachability requires local low-privileged access and a TCP-AO-enabled socket path; repeated failures consume kernel memory and can deny service.

The record

CVE
CVE-2025-39852
Published
Sep 19, 2025
Updated
Sep 19, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-401, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 19, 2025CVE publishedPublication date reported by the CVE source.
  2. Sep 19, 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=06b22ef29591f625ef877ae00d82192938e29e60 <3d2b356d994a8801acb397cafd28b13672c37ab5
  2. Affected versionversion=06b22ef29591f625ef877ae00d82192938e29e60 <46d33c878fc0b3d7570366b2c9912395b3f4e701
  3. Affected versionversion=06b22ef29591f625ef877ae00d82192938e29e60 <fa390321aba0a54d0f7ae95ee4ecde1358bb9234
  4. Affected versionversion=6.7

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=06b22ef29591f625ef877ae00d82192938e29e60 <3d2b356d994a8801acb397cafd28b13672c37ab5; version=06b22ef29591f625ef877ae00d82192938e29e60 <46d33c878fc0b3d7570366b2c9912395b3f4e701; version=06b22ef29591f625ef877ae00d82192938e29e60 <fa390321aba0a54d0f7ae95ee4ecde1358bb9234; version=6.7

Published CVSS scores

5.5NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5UbuntuCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5CISA-ADPCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5Amazon LinuxCVSS: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

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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-401Missing Release of Memory after Effective Lifetime
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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