CVE-2023-53133

Local CPU soft lockup via zero-length recvmsg

Published May 2, 2025 · Updated Jun 1, 2026

Denial of service in Linux allows local users to cause a CPU soft lockup through a zero-length recvmsg call on a BPF sockmap socket. In tcp_bpf_recvmsg_parser, sk_msg_recvmsg returns zero for a zero-byte request, but the caller waits for data and jumps back to the same receive label instead of returning. Low-privileged local access and a socket using the BPF stream parser are required; the resulting loop can leave a CPU stuck and interrupt service without exposing or altering data.

CVSS severity5.5
Medium
EPSS probability0.18%
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 Linux allows local users to cause a CPU soft lockup through a zero-length recvmsg call on a BPF sockmap socket. In tcp_bpf_recvmsg_parser, sk_msg_recvmsg returns zero for a zero-byte request, but the caller waits for data and jumps back to the same receive label instead of returning. Low-privileged local access and a socket using the BPF stream parser are required; the resulting loop can leave a CPU stuck and interrupt service without exposing or altering data.

The record

CVE
CVE-2023-53133
Published
May 2, 2025
Updated
Jun 1, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 2, 2025CVE publishedPublication date reported by the CVE source.
  2. Jun 1, 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=4.20
  2. Affected versionversion=604326b41a6fb9b4a78b6179335decee0365cd8c <4a476285f6d2921c3c9faa494eab83b78f78fc55
  3. Affected versionversion=604326b41a6fb9b4a78b6179335decee0365cd8c <bf0579989de64d36e177c0611c685dc4a91457a7
  4. Affected versionversion=604326b41a6fb9b4a78b6179335decee0365cd8c <d900f3d20cc3169ce42ec72acc850e662a4d4db2
  5. Affected versionversion=604326b41a6fb9b4a78b6179335decee0365cd8c <f0d52cc242f279c422b487dcaaccd98b99672fd0
  6. Affected versionversion=604326b41a6fb9b4a78b6179335decee0365cd8c <f45cf3ae3068e70e2c7f3e24a7f8e8aa99511f03

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=4.20; version=604326b41a6fb9b4a78b6179335decee0365cd8c <4a476285f6d2921c3c9faa494eab83b78f78fc55; version=604326b41a6fb9b4a78b6179335decee0365cd8c <bf0579989de64d36e177c0611c685dc4a91457a7; version=604326b41a6fb9b4a78b6179335decee0365cd8c <d900f3d20cc3169ce42ec72acc850e662a4d4db2; version=604326b41a6fb9b4a78b6179335decee0365cd8c <f0d52cc242f279c422b487dcaaccd98b99672fd0; version=604326b41a6fb9b4a78b6179335decee0365cd8c <f45cf3ae3068e70e2c7f3e24a7f8e8aa99511f03

Published CVSS scores

5.5CanonicalCVSS: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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.004Application or System Exploitation

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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