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.
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.
Metrics
Affected Vendors & Products
Advisories
| Source | ID | Title |
|---|---|---|
Debian DLA |
DLA-4327-1 | linux security update |
Debian DLA |
DLA-4328-1 | linux-6.1 security update |
Debian DSA |
DSA-6008-1 | linux security update |
Debian DSA |
DSA-6009-1 | linux security update |
EUVD |
EUVD-2025-31557 | 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. |
Ubuntu USN |
USN-7909-1 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-7909-2 | Linux kernel (Real-time) vulnerabilities |
Ubuntu USN |
USN-7909-3 | Linux kernel (FIPS) vulnerabilities |
Ubuntu USN |
USN-7910-1 | Linux kernel (Azure FIPS) vulnerabilities |
Ubuntu USN |
USN-7909-4 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-7910-2 | Linux kernel (Azure) vulnerabilities |
Ubuntu USN |
USN-7909-5 | Linux kernel (Raspberry Pi) vulnerabilities |
Ubuntu USN |
USN-7933-1 | Linux kernel (KVM) vulnerabilities |
Ubuntu USN |
USN-7938-1 | Linux kernel (Azure) vulnerabilities |
Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Mon, 03 Nov 2025 18:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| References |
|
Sat, 06 Sep 2025 09:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Linux
Linux linux Kernel |
|
| Vendors & Products |
Linux
Linux linux Kernel |
Sat, 06 Sep 2025 00:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| References |
| |
| Metrics |
threat_severity
|
cvssV3_1
|
Fri, 05 Sep 2025 17:30:00 +0000
| Type | Values Removed | Values 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. | |
| Title | netfilter: nf_reject: don't leak dst refcount for loopback packets | |
| References |
|
|
Projects
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Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2025-11-03T17:42:03.823Z
Reserved: 2025-04-16T04:51:24.033Z
Link: CVE-2025-38732
No data.
Status : Awaiting Analysis
Published: 2025-09-05T18:15:42.407
Modified: 2025-11-03T18:16:38.177
Link: CVE-2025-38732
OpenCVE Enrichment
Updated: 2025-09-06T09:01:33Z
Weaknesses
No weakness.
Debian DLA
Debian DSA
EUVD
Ubuntu USN