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CVE-2025-38732

5.5 · MEDIUM

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_reject: don't leak dst refcount for loopback packets recent patches to add a WARN() when replacing skb dst entry…

Published Sep 5, 2025EPSS 0.18%

Overview

CVE-2025-38732 is a medium-severity vulnerability. It was published on September 5, 2025 and has a CVSS 3.1 base score of 5.5 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 5.5, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

Technical description

In the Linux kernel, the following vulnerability has been resolved:

netfilter: nf_reject: don't leak dst refcount for loopback packets

recent patches to add a WARN() when replacing skb dst entry found an

old bug:

WARNING: include/linux/skbuff.h:1165 skb_dst_check_unset include/linux/skbuff.h:1164 [inline]

WARNING: include/linux/skbuff.h:1165 skb_dst_set include/linux/skbuff.h:1210 [inline]

WARNING: include/linux/skbuff.h:1165 nf_reject_fill_skb_dst+0x2a4/0x330 net/ipv4/netfilter/nf_reject_ipv4.c:234

[..]

Call Trace:

nf_send_unreach+0x17b/0x6e0 net/ipv4/netfilter/nf_reject_ipv4.c:325

nft_reject_inet_eval+0x4bc/0x690 net/netfilter/nft_reject_inet.c:27

expr_call_ops_eval net/netfilter/nf_tables_core.c:237 [inline]

..

This is because blamed commit forgot about loopback packets.

Such packets already have a dst_entry attached, even at PRE_ROUTING stage.

Instead of checking hook just check if the skb already has a route

attached to it.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refgit.kernel.org/stable/c/51e8531371f90bee742c63775c9a568e5d6bf3c5Refgit.kernel.org/stable/c/7b8b503c06274ef3c6c1a107743f1ec0d0a53ef8Refgit.kernel.org/stable/c/82ef97abf22790182f7d433c74960dfd61b99c33Refgit.kernel.org/stable/c/91a79b792204313153e1bdbbe5acbfc28903b3a5Refgit.kernel.org/stable/c/a0a3ace2a57887dac1e7c9a724846040c3e31868Refgit.kernel.org/stable/c/b32e1590a8d22cf7d7f965e46d5576051acf8e42Refgit.kernel.org/stable/c/b7a885ba25960c91db237c3f83b4285156789bceReflists.debian.org/debian-lts-announce/2025/10/msg00007.htmlReflists.debian.org/debian-lts-announce/2025/10/msg00008.htmlRefcert-portal.siemens.com/productcert/html/ssa-019113.html

How CyberStrike helps

Frequently asked questions

What is CVE-2025-38732?

CVE-2025-38732 is a medium-severity vulnerability. It was published on September 5, 2025 and has a CVSS 3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2025-38732?

This vulnerability has a CVSS 3.1 base score of 5.5, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2025-38732?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2025-38732?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2025-38732 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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