CVE-2025-22021: netfilter: socket: Lookup orig tuple for IPv6 SNAT
Vulnerability summary
CVE-2025-22021 is a critical (CVSS 10.0) vulnerability in linux. EPSS estimates a 0.47% chance of exploitation in the next 30 days, higher than 40.7% of scored vulnerabilities.
Severe, CVSS 10 (CVE.org); no exploitation reported by the 5 checked sources; EPSS 0% (FIRST, 03-11-2026)
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 54 · Related 50Timeline
- 16-04-2025PublishedVulnerability first disclosed.
- 15-10-2026Last modifiedVulnerability information updated.
Description
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.
CVSS metrics
5 scores · 4 sources · 2 versions- OSV · UbuntuEcosystem advisory · calculated10.0CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
- OSV · DebianEcosystem advisory · calculated5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HDiffers
- NVDNIST5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HDiffers
EPSS trend
Probability
0.47%
Chance of exploitation in the next 30 days
Percentile
41%
Versus all other CVEs
30-day change
Increase +0.01 pp
From 0.46% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeNo weakness data has been published for this record.
Affected systems
Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.
Ubuntu137 products
- linuxAll versions (No fix recorded) | < 5.4.0-218.238 | < 5.15.0-142.152 | < 6.8.0-86.87
- linux-allwinner-5.19All versions (No fix recorded)
- linux-awsAll versions (No fix recorded) | < 5.4.0-1147.157 | < 5.15.0-1086.93 | < 6.8.0-1041.43
- linux-aws-5.0All versions (No fix recorded)
- linux-aws-5.11All versions (No fix recorded)
Linux2 products
- linux≥ eb31628e37a0a4e01fffd79dcc7f815d2357f53a, < 6488b96a79a26e19100ad872622f04e93b638d7f | ≥ eb31628e37a0a4e01fffd79dcc7f815d2357f53a, < 58ab63d3ded2ca6141357a2b24eee8453d0f871d | ≥ eb31628e37a0a4e01fffd79dcc7f815d2357f53a, < 1ca2169cc19dca893c7aae6af122852097435d16 | ≥ eb31628e37a0a4e01fffd79dcc7f815d2357f53a, < 1ec43100f7123010730b7ddfc3d5c2eac19e70e7 | ≥ eb31628e37a0a4e01fffd79dcc7f815d2357f53a, < 5251041573850e5020cd447374e23010be698898 | ≥ eb31628e37a0a4e01fffd79dcc7f815d2357f53a, < 2bb139e483f8cbe488d19d8c1135ac3615e2668c | ≥ eb31628e37a0a4e01fffd79dcc7f815d2357f53a, < 41904cbb343d115931d6bf79aa2c815cac4ef72b | ≥ eb31628e37a0a4e01fffd79dcc7f815d2357f53a, < 221c27259324ec1404f028d4f5a0f2ae7f63ee23 | ≥ eb31628e37a0a4e01fffd79dcc7f815d2357f53a, < 932b32ffd7604fb00b5c57e239a3cc4d901ccf6e | 3.13
- linux_kernelEOL≥ 3.13, < 5.4.292 | ≥ 5.5, < 5.10.236 | ≥ 5.11, < 5.15.180 | ≥ 5.16, < 6.1.133 | ≥ 6.2, < 6.6.86 | ≥ 6.7, < 6.12.22 | ≥ 6.13, < 6.13.10 | 6.14
Debian1 product
- linux< 6.1.133-1 | < 6.12.22-1
3 vendors · 140 products
