# CVE-2025-38732

## Summary

- **CVE ID:** CVE-2025-38732
- **Severity:** MEDIUM
- **CVSS Score:** 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)
- **CWE:** N/A
- **Published:** Sep 5, 2025
- **Last Modified:** Sep 8, 2026

## 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.

## Affected Products

- Linux — Linux (f53b9b0bdc59c0823679f2e3214e0d538f5951b9)
- Linux — Linux (5.9)
- Linux — Linux (0)
- Linux — Linux (5.10.241)
- Linux — Linux (5.15.190)
- Linux — Linux (6.1.149)
- Linux — Linux (6.6.103)
- Linux — Linux (6.12.44)
- Linux — Linux (6.16.4)
- Linux — Linux (6.17)

## References

- [CNA](https://git.kernel.org/stable/c/7b8b503c06274ef3c6c1a107743f1ec0d0a53ef8)
- [CNA](https://git.kernel.org/stable/c/82ef97abf22790182f7d433c74960dfd61b99c33)
- [CNA](https://git.kernel.org/stable/c/b7a885ba25960c91db237c3f83b4285156789bce)
- [CNA](https://git.kernel.org/stable/c/a0a3ace2a57887dac1e7c9a724846040c3e31868)
- [CNA](https://git.kernel.org/stable/c/51e8531371f90bee742c63775c9a568e5d6bf3c5)
- [CNA](https://git.kernel.org/stable/c/b32e1590a8d22cf7d7f965e46d5576051acf8e42)
- [CNA](https://git.kernel.org/stable/c/91a79b792204313153e1bdbbe5acbfc28903b3a5)
- [CVE](https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html)
- [CVE](https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html)
- [siemens-SADP](https://cert-portal.siemens.com/productcert/html/ssa-032379.html)
- [siemens-SADP](https://cert-portal.siemens.com/productcert/html/ssa-019113.html)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.17%
- **EPSS Percentile:** 6.7

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-17._