CVE-2025-22021

Medium

In the Linux kernel, the following vulnerability has been resolved: netfilter: socket: Lookup orig tuple for IPv6 SNAT nf_sk_lookup_slow_v4 does the conntrack lookup for IPv4 packets to restore the original 5-tuple in case of SNAT, to be able to find the right socket (if any). Then socket_match() can correctly check whether the socket was transparent. However, the IPv6 counterpart (nf_sk_lookup_slow_v6) lacks this conntrack lookup, making xt_socket fail to match on the socket when the packet was SNATed. Add the same logic to nf_sk_lookup_slow_v6. IPv6 SNAT is used in Kubernetes clusters for pod-to-world packets, as pods' addresses are in the fd00::/8 ULA subnet and need to be replaced with the node's external address. Cilium leverages Envoy to enforce L7 policies, and Envoy uses transparent sockets. Cilium inserts an iptables prerouting rule that matches on `-m socket --transparent` and redirects the packets to localhost, but it fails to match SNATed IPv6 packets due to that missing conntrack lookup.

Package Linux Kernel
Published 2025-04-16
Last modified 2025-11-03
CVSS version 3.1
Patch available
Yes

CVSS 3.1 score

5.5

out of 10
Medium
Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
High
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected versions

Linux kernel versions 3.13 and later are affected. Fixed in 5.4.292, 5.10.236, 5.15.180, 6.1.133, 6.6.86, 6.12.22, 6.13.10, 6.14.1, 6.15 and their respective stable series.

Affected from
≥ 3.13
Fixed in
✓ 5.4.292 5.4.x ✓ 5.10.236 5.10.x ✓ 5.15.180 5.15.x ✓ 6.1.133 6.1.x ✓ 6.6.86 6.6.x ✓ 6.12.22 6.12.x ✓ 6.13.10 6.13.x ✓ 6.14.1 6.14.x ✓ 6.15

References

The following references provide additional information about CVE-2025-22021 including vendor advisories, patch commits, exploit details, and third-party analysis. Links are sourced from the NIST NVD database.

9 patch commits total View all on NVD

Frequently asked questions

  • What is CVE-2025-22021?

    CVE-2025-22021 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10 . It affects Linux kernel versions from 3.13 onward and has been patched in 5.4.292, 5.10.236, 5.15.180 and others. CVE-2025-22021 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

  • What is the CVSS score for CVE-2025-22021?

    CVE-2025-22021 has a CVSS score of 5.5 out of 10, rated Medium severity (CVSS 3.1). The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H .

  • Is there a patch available for CVE-2025-22021?

    Yes — CVE-2025-22021 has been patched. Fixed versions include 5.4.292, 5.10.236, 5.15.180 and others. If you are running Linux kernel 3.13 or later up to the fix versions, apply the relevant patch for your kernel branch.

  • Is CVE-2025-22021 actively exploited?

    No — CVE-2025-22021 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

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