CVE-2023-53809Public exploit

Local denial of service via recursive socket locking

Published Dec 9, 2025 · Updated May 23, 2026

Denial of service in affected Linux kernel releases allows local users to hang PPPoL2TP setup via a crafted socket descriptor. pppol2tp_connect holds the PPPoL2TP socket lock while l2tp_tunnel_register reuses that socket as the tunnel UDP descriptor and attempts to acquire the lock again. A local low-privileged process able to create and connect an AF_PPPOX socket can stall its task; no confidentiality or integrity impact is reported.

CVSS severity5.5
Medium
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

Denial of service in affected Linux kernel releases allows local users to hang PPPoL2TP setup via a crafted socket descriptor. pppol2tp_connect holds the PPPoL2TP socket lock while l2tp_tunnel_register reuses that socket as the tunnel UDP descriptor and attempts to acquire the lock again. A local low-privileged process able to create and connect an AF_PPPOX socket can stall its task; no confidentiality or integrity impact is reported.

The record

CVE
CVE-2023-53809
Published
Dec 9, 2025
Updated
May 23, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Dec 9, 2025CVE publishedPublication date reported by the CVE source.
  2. May 23, 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=0b2c59720e65885a394a017d0cf9cab118914682 <5370647dd745bb3d8f37057006be207ddd8e9314
  2. Affected versionversion=0b2c59720e65885a394a017d0cf9cab118914682 <9ca5e7ecab064f1f47da07f7c1ddf40e4bc0e5ac
  3. Affected versionversion=2d77e5c0ad79004b5ef901895437e9cce6dfcc7e <4a413d360959962995e16a899cf2b9ef53e9fcb9
  4. Affected versionversion=5.10.166 <5.10.173
  5. Affected versionversion=5.15.91 <5.15.99
  6. Affected versionversion=6.1.9 <6.1.16
  7. Affected versionversion=6.2
  8. Affected versionversion=77e8ed776cdb1a24b2aab8fe7c6f1f154235e1ce <f6df58aa15f7d469f69b1dd21b001ff483255244
  9. Affected versionversion=cef0845b6dcfa2f6c2c832e7f9622551456c741d <4bb736b40475528ac1aa8c98b368563618488a70

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=0b2c59720e65885a394a017d0cf9cab118914682 <5370647dd745bb3d8f37057006be207ddd8e9314; version=0b2c59720e65885a394a017d0cf9cab118914682 <9ca5e7ecab064f1f47da07f7c1ddf40e4bc0e5ac; version=2d77e5c0ad79004b5ef901895437e9cce6dfcc7e <4a413d360959962995e16a899cf2b9ef53e9fcb9; version=5.10.166 <5.10.173; version=5.15.91 <5.15.99; version=6.1.9 <6.1.16; version=6.2; version=77e8ed776cdb1a24b2aab8fe7c6f1f154235e1ce <f6df58aa15f7d469f69b1dd21b001ff483255244; version=cef0845b6dcfa2f6c2c832e7f9622551456c741d <4bb736b40475528ac1aa8c98b368563618488a70

Published CVSS scores

5.5SUSECVSS: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 exploitPublished

Weakness, pattern, technique

T1499Endpoint Denial of Service

Public exploit references

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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