CVE-2025-21629Network attack vector

Host crash via disabled BIG TCP checksum offload

Published Jan 15, 2025 · Updated Aug 5, 2026

Denial of service in Linux kernel BIG TCP handling allows remote attackers to crash hosts via crafted IPv6 jumbogram traffic. net/core/dev.c sends eligible jumbograms through software checksum handling after NETIF_F_IPV6_CSUM offload is disabled, causing skb_warn_bad_offload to warn, dump packet data, and discard the packet. A BIG-TCP-enabled host with a supported NIC is required; panic_on_warn causes a crash, while other hosts lose affected packets and expose bounded payload data in kernel logs.

CVSS severity8.2
High
EPSS probability0.43%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Denial of service in Linux kernel BIG TCP handling allows remote attackers to crash hosts via crafted IPv6 jumbogram traffic. net/core/dev.c sends eligible jumbograms through software checksum handling after NETIF_F_IPV6_CSUM offload is disabled, causing skb_warn_bad_offload to warn, dump packet data, and discard the packet. A BIG-TCP-enabled host with a supported NIC is required; panic_on_warn causes a crash, while other hosts lose affected packets and expose bounded payload data in kernel logs.

The record

CVE
CVE-2025-21629
Published
Jan 15, 2025
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 15, 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=04c20a9356f283da623903e81e7c6d5df7e4dc3c <68e068cabd2c6c533ef934c2e5151609cf6ecc6d
  2. Affected versionversion=04c20a9356f283da623903e81e7c6d5df7e4dc3c <d3b7a9c7597b779039a51d7b34116fbe424bf2b7
  3. Affected versionversion=4.19.323 <4.20
  4. Affected versionversion=477b35d94a21530046fe91589960732fcf2b29ed
  5. Affected versionversion=5.10.229 <5.11
  6. Affected versionversion=5.15.171 <5.16
  7. Affected versionversion=5.4.285 <5.5
  8. Affected versionversion=6.1.116 <6.1.124
  9. Affected versionversion=6.11.7 <6.12
  10. Affected versionversion=6.12
  11. Affected versionversion=6.6.60 <6.6.70
  12. Affected versionversion=705350fbd6ed4b5d89ee045fa57a0594a72b17d7
  13. Affected versionversion=9f605135a5c0fe614c2b15197b9ced1e217eca59
  14. Affected versionversion=a27a5c40ee4cbe00294e2c76160de5f2589061ba
  15. Affected versionversion=a84978a9cda68f0afe3f01d476c68db21526baf1 <ac9cfef69565021c9e1022a493a9c40b03e2caf9
  16. Affected versionversion=bcefc3cd7f592a70fcbbbfd7ad1fbc69172ea78b
  17. Affected versionversion=c69bc67c1cb211aa390bea6e512bb01b1241fefb <95ccf006bbc8b59044313b8c309dcf29c546abd4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=04c20a9356f283da623903e81e7c6d5df7e4dc3c <68e068cabd2c6c533ef934c2e5151609cf6ecc6d; version=04c20a9356f283da623903e81e7c6d5df7e4dc3c <d3b7a9c7597b779039a51d7b34116fbe424bf2b7; version=4.19.323 <4.20; version=477b35d94a21530046fe91589960732fcf2b29ed; version=5.10.229 <5.11; version=5.15.171 <5.16; version=5.4.285 <5.5; version=6.1.116 <6.1.124; version=6.11.7 <6.12; version=6.12; version=6.6.60 <6.6.70; version=705350fbd6ed4b5d89ee045fa57a0594a72b17d7; version=9f605135a5c0fe614c2b15197b9ced1e217eca59; version=a27a5c40ee4cbe00294e2c76160de5f2589061ba; version=a84978a9cda68f0afe3f01d476c68db21526baf1 <ac9cfef69565021c9e1022a493a9c40b03e2caf9; version=bcefc3cd7f592a70fcbbbfd7ad1fbc69172ea78b; version=c69bc67c1cb211aa390bea6e512bb01b1241fefb <95ccf006bbc8b59044313b8c309dcf29c546abd4

Published CVSS scores

5.5UbuntuCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
8.2LinuxCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/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

T1499.004Application or System Exploitation

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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo