CVE-2025-21720Network attack vector

Gateway crash via retained XFRM secpath

Published Feb 27, 2025 · Updated Aug 5, 2026

Denial of service in the Linux XFRM subsystem allows remote attackers to crash IPsec offload gateways with a forwarded packet. In forwarding mode, XFRM policy checking leaves a hardware-added secpath attached, so the packet reenters the driver transmit path with xfrm_offload set and calls a null set_iv_op pointer. IP forwarding and IPsec packet offload must both be enabled; a triggering inbound packet panics the kernel and forces a reboot.

CVSS severity7.5
High
EPSS probability0.36%
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 the Linux XFRM subsystem allows remote attackers to crash IPsec offload gateways with a forwarded packet. In forwarding mode, XFRM policy checking leaves a hardware-added secpath attached, so the packet reenters the driver transmit path with xfrm_offload set and calls a null set_iv_op pointer. IP forwarding and IPsec packet offload must both be enabled; a triggering inbound packet panics the kernel and forces a reboot.

The record

CVE
CVE-2025-21720
Published
Feb 27, 2025
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 27, 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

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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=5958372ddf628fe6f4c3e49425734ad32fcfb13c <600258d555f0710b9c47fb78d2d80a4aecd608cc
  2. Affected versionversion=5958372ddf628fe6f4c3e49425734ad32fcfb13c <6945701ca1572f81bc9bb46f624b02eabb3eaf3e
  3. Affected versionversion=5958372ddf628fe6f4c3e49425734ad32fcfb13c <981ad4c882096e7375b8c2181dd4c3ee58ea5bae
  4. Affected versionversion=5958372ddf628fe6f4c3e49425734ad32fcfb13c <c6e1b2cac24b2a4d1dd472071021bf00c26450eb
  5. Affected versionversion=6.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5958372ddf628fe6f4c3e49425734ad32fcfb13c <600258d555f0710b9c47fb78d2d80a4aecd608cc; version=5958372ddf628fe6f4c3e49425734ad32fcfb13c <6945701ca1572f81bc9bb46f624b02eabb3eaf3e; version=5958372ddf628fe6f4c3e49425734ad32fcfb13c <981ad4c882096e7375b8c2181dd4c3ee58ea5bae; version=5958372ddf628fe6f4c3e49425734ad32fcfb13c <c6e1b2cac24b2a4d1dd472071021bf00c26450eb; version=6.2

Published CVSS scores

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.

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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)
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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