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CVE-2025-38732
netfilter: nf_reject: don't leak dst refcount for loopback packets
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.

INFO

Published Date :

Sept. 5, 2025, 6:15 p.m.

Last Modified :

Sept. 5, 2025, 6:15 p.m.

Remotely Exploit :

No

Source :

416baaa9-dc9f-4396-8d5f-8c081fb06d67
Affected Products

The following products are affected by CVE-2025-38732 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

No affected product recoded yet

: Total Affected Vendor : 0 | Products : 0
Solution
Update Linux kernel to prevent resource leaks when handling loopback packets.
  • Update the Linux kernel to the latest stable version.
  • Apply the provided patch for netfilter: nf_reject.
  • Ensure skb has a route attached before processing.
  • Test the fix on loopback packet handling.
References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2025-38732.

URL Resource
https://git.kernel.org/stable/c/51e8531371f90bee742c63775c9a568e5d6bf3c5
https://git.kernel.org/stable/c/7b8b503c06274ef3c6c1a107743f1ec0d0a53ef8
https://git.kernel.org/stable/c/82ef97abf22790182f7d433c74960dfd61b99c33
https://git.kernel.org/stable/c/91a79b792204313153e1bdbbe5acbfc28903b3a5
https://git.kernel.org/stable/c/a0a3ace2a57887dac1e7c9a724846040c3e31868
https://git.kernel.org/stable/c/b32e1590a8d22cf7d7f965e46d5576051acf8e42
https://git.kernel.org/stable/c/b7a885ba25960c91db237c3f83b4285156789bce
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2025-38732 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2025-38732 weaknesses.

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2025-38732 vulnerability anywhere in the article.

Results are limited to the first 20 news articles due to potential performance issues.

The following table lists the changes that have been made to the CVE-2025-38732 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    Sep. 05, 2025

    Action Type Old Value New Value
    Added 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.
    Added Reference https://git.kernel.org/stable/c/51e8531371f90bee742c63775c9a568e5d6bf3c5
    Added Reference https://git.kernel.org/stable/c/7b8b503c06274ef3c6c1a107743f1ec0d0a53ef8
    Added Reference https://git.kernel.org/stable/c/82ef97abf22790182f7d433c74960dfd61b99c33
    Added Reference https://git.kernel.org/stable/c/91a79b792204313153e1bdbbe5acbfc28903b3a5
    Added Reference https://git.kernel.org/stable/c/a0a3ace2a57887dac1e7c9a724846040c3e31868
    Added Reference https://git.kernel.org/stable/c/b32e1590a8d22cf7d7f965e46d5576051acf8e42
    Added Reference https://git.kernel.org/stable/c/b7a885ba25960c91db237c3f83b4285156789bce
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.
Vulnerability Scoring Details
No CVSS metrics available for this vulnerability.