From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-cve-announce@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@kernel.org>
Subject: CVE-2026-74569: netfilter: nf_conntrack_sip: widen NAT rewrite delta to s32 in sip_help_tcp()
Date: Sat, 15 Aug 2026 21:27:30 +0900 [thread overview]
Message-ID: <2026081554-CVE-2026-74569-45bc@gregkh> (raw)
From: Greg Kroah-Hartman <gregkh@kernel.org>
Description
===========
In the Linux kernel, the following vulnerability has been resolved:
netfilter: nf_conntrack_sip: widen NAT rewrite delta to s32 in sip_help_tcp()
sip_help_tcp() stores the size change of each NAT-rewritten SIP message
in s16 diff and accumulates it in s16 tdiff, but a single message can
grow by more than S16_MAX while the packet stays under the 65535
enlarge_skb() limit: nf_nat_sip() rewrites every matching URI, and a long
Contact list expands the message by tens of kilobytes. diff then wraps,
and "datalen = datalen + diff - msglen" yields a huge unsigned datalen,
so the next iteration's ct_sip_get_header() reads past the linearized skb
tail.
Widen diff, tdiff and the seq_adjust hook to s32. Both are bounded by the
65535 byte packet limit, and the seqadj core is already s32
(nf_ct_seqadj_set() takes s32), so no previously accepted input is
rejected.
BUG: KASAN: use-after-free in ct_sip_get_header (net/netfilter/nf_conntrack_sip.c:464)
Read of size 1 at addr ffff888010800000 by task ksoftirqd/1/25
ct_sip_get_header (net/netfilter/nf_conntrack_sip.c:464)
sip_help_tcp (net/netfilter/nf_conntrack_sip.c:1694)
nf_confirm (net/netfilter/nf_conntrack_proto.c:183)
nf_hook_slow (net/netfilter/core.c:619)
ip6_output (net/ipv6/ip6_output.c:246)
ip6_forward (net/ipv6/ip6_output.c:690)
ipv6_rcv (net/ipv6/ip6_input.c:351)
__netif_receive_skb_one_core (net/core/dev.c:6212)
process_backlog (net/core/dev.c:6676)
__napi_poll (net/core/dev.c:7735)
net_rx_action (net/core/dev.c:7955)
handle_softirqs (kernel/softirq.c:622)
run_ksoftirqd (kernel/softirq.c:1076)
...
The Linux kernel CVE team has assigned CVE-2026-74569 to this issue.
Affected and fixed versions
===========================
Issue introduced in 2.6.34 with commit f5b321bd37fbec9188feb1f721ab46a5ac0b35da and fixed in 6.6.151 with commit 63eea41759fd682229c14e0a2205802b46d106f3
Issue introduced in 2.6.34 with commit f5b321bd37fbec9188feb1f721ab46a5ac0b35da and fixed in 6.12.103 with commit c97621a110e386b2dd69e276eb699e1d3cec581d
Issue introduced in 2.6.34 with commit f5b321bd37fbec9188feb1f721ab46a5ac0b35da and fixed in 6.18.44 with commit f74554e67ccf04d1fa71069e8c9afa2717e40716
Issue introduced in 2.6.34 with commit f5b321bd37fbec9188feb1f721ab46a5ac0b35da and fixed in 7.1.8 with commit ef5e2c6555d2bb52dfe0e4053a8c6193f9d83b64
Issue introduced in 2.6.34 with commit f5b321bd37fbec9188feb1f721ab46a5ac0b35da and fixed in 7.2-rc6 with commit db3d0e0e5d4bc5ab4fe445b9f413d1b486508ca5
Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.
Unaffected versions might change over time as fixes are backported to
older supported kernel versions. The official CVE entry at
https://cve.org/CVERecord/?id=CVE-2026-74569
will be updated if fixes are backported, please check that for the most
up to date information about this issue.
Affected files
==============
The file(s) affected by this issue are:
include/linux/netfilter/nf_conntrack_sip.h
net/netfilter/nf_conntrack_sip.c
net/netfilter/nf_nat_sip.c
Mitigation
==========
The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes. Individual
changes are never tested alone, but rather are part of a larger kernel
release. Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all. If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
https://git.kernel.org/stable/c/63eea41759fd682229c14e0a2205802b46d106f3
https://git.kernel.org/stable/c/c97621a110e386b2dd69e276eb699e1d3cec581d
https://git.kernel.org/stable/c/f74554e67ccf04d1fa71069e8c9afa2717e40716
https://git.kernel.org/stable/c/ef5e2c6555d2bb52dfe0e4053a8c6193f9d83b64
https://git.kernel.org/stable/c/db3d0e0e5d4bc5ab4fe445b9f413d1b486508ca5
reply other threads:[~2026-08-15 12:33 UTC|newest]
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