CVE-2025-38732
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2025-09-05

Last updated on: 2025-11-03

Assigner: kernel.org

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.
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Meta Information
Published
2025-09-05
Last Modified
2025-11-03
Generated
2026-06-16
AI Q&A
2025-09-05
EPSS Evaluated
2026-06-15
NVD
CVE-2025-38732
Affected Vendors & Products
Showing 2 associated CPEs
Vendor Product Version / Range
linux kernel 5.10.244-1
linux kernel 6.1.153-1
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Exploitability
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CWE ID Description
CWE-UNKNOWN
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Executive Summary

This vulnerability in the Linux kernel's netfilter component involves improper handling of loopback packets in the nf_reject module. Specifically, a recent patch added warnings when replacing the skb (socket buffer) destination entry but overlooked that loopback packets already have a destination entry attached even at the PRE_ROUTING stage. This caused a reference count leak for the destination entry of loopback packets. The fix involves checking if the skb already has a route attached rather than relying on the hook stage.

Impact Analysis

The vulnerability can lead to a leak of the destination reference count for loopback packets, which may cause resource mismanagement within the kernel's networking stack. This could potentially result in degraded system performance or instability due to improper handling of network packet routing information.

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