CVE-2026-52986
published 2026-06-24CVE-2026-52986: In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_sip: don't use simple_strtoul Replace unsafe port parsing in…
PriorityP357critical9.8CVSS 3.1
AVNACLPRNUINSUCHIHAH
EPSS
0.56%
42.6th percentile
In the Linux kernel, the following vulnerability has been resolved:
netfilter: nf_conntrack_sip: don't use simple_strtoul
Replace unsafe port parsing in epaddr_len(), ct_sip_parse_header_uri(),
and ct_sip_parse_request() with a new sip_parse_port() helper that
validates each digit against the buffer limit, eliminating the use of
simple_strtoul() which assumes NUL-terminated strings.
The previous code dereferenced pointers without bounds checks after
sip_parse_addr() and relied on simple_strtoul() on non-NUL-terminated
skb data. A port that reaches the buffer limit without a trailing
character is also rejected as malformed.
Also get rid of all simple_strtoul() usage in conntrack, prefer a
stricter version instead. There are intentional changes:
- Bail out if number is > UINT_MAX and indicate a failure, same for
too long sequences.
While we do accept 05535 as port 5535, we will not accept e.g.
'sip:10.0.0.1:005060'. While its syntactically valid under RFC 3261,
we should restrict this to not waste cycles when presented with
malformed packets with 64k '0' characters.
- Force base 10 in ct_sip_parse_numerical_param(). This is used to fetch
'expire=' and 'rports='; both are expected to use base-10.
- In nf_nat_sip.c, only accept the parsed value if its within the 1k-64k
range.
- epaddr_len now returns 0 if the port is invalid, as it already does
for invalid ip addresses. This is intentional. nf_conntrack_sip
performs lots of guesswork to find the right parts of the message
to parse. Being stricter could break existing setups.
Connection tracking helpers are designed to allow traffic to
pass, not to block it.
Based on an earlier patch from Jenny Guanni Qu .
Affected
10 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| linux | linux | — | — |
| linux | linux | >= 05e3ced297fe755093140e7487e292fb7603316e < 8cd0358379570003659186706e077929d6930c40 | 8cd0358379570003659186706e077929d6930c40 |
| linux | linux | >= 05e3ced297fe755093140e7487e292fb7603316e < 9c6afcb1c3cbb2c0da65b8515ac14d7273872f84 | 9c6afcb1c3cbb2c0da65b8515ac14d7273872f84 |
| linux | linux | >= 05e3ced297fe755093140e7487e292fb7603316e < b3264c977e79d8a25778d4fd11520f00fea1329c | b3264c977e79d8a25778d4fd11520f00fea1329c |
| linux | linux | >= 05e3ced297fe755093140e7487e292fb7603316e < ea2ecd29b8f4433e52607192ca91084f95787ca0 | ea2ecd29b8f4433e52607192ca91084f95787ca0 |
| linux | linux | >= 05e3ced297fe755093140e7487e292fb7603316e < 9f69c323ae0ab517e595c2cc74e0ae0d9d085611 | 9f69c323ae0ab517e595c2cc74e0ae0d9d085611 |
| linux | linux | >= 05e3ced297fe755093140e7487e292fb7603316e < 7df9863bf538a626e8a684e59cb2c43eac0ef3c8 | 7df9863bf538a626e8a684e59cb2c43eac0ef3c8 |
| linux | linux | >= 05e3ced297fe755093140e7487e292fb7603316e < 523762e3b6933fff81f01dfa3c60c0774044cdab | 523762e3b6933fff81f01dfa3c60c0774044cdab |
| linux | linux | >= 05e3ced297fe755093140e7487e292fb7603316e < 8cf6809cddcbe301aedfc6b51bcd4944d45795f6 | 8cf6809cddcbe301aedfc6b51bcd4944d45795f6 |
| linux | linux_kernel | — | — |
CVSS provenance
nvdv3.19.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
vendor_redhat7.0MEDIUM
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GHSA
In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_sip: don't use simple_strtoul Replace unsafe port parsing in epaddr_len(), ct_sip_parse_header_uri(), and
ghsa_unreviewed·2026-06-24
CVE-2026-52986 In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_sip: don't use simple_strtoul Replace unsafe port parsing in epaddr_len(), ct_sip_parse_header_uri(), and
In the Linux kernel, the following vulnerability has been resolved:
netfilter: nf_conntrack_sip: don't use simple_strtoul
Replace unsafe port parsing in epaddr_len(), ct_sip_parse_header_uri(),
and ct_sip_parse_request() with a new sip_parse_port() helper that
validates each digit against the buffer limit, eliminating the use of
simple_strtoul() which assumes NUL-terminated strings.
The previous code dereferenced pointers without bounds checks after
sip_parse_addr() and relied on simple_strtoul() on non-NUL-terminated
skb data. A port that reaches the buffer limit without a trailing
character is also rejected as malformed.
Also get rid of all simple_strtoul() usage in conntrack, prefer a
stricter version instead. There are intentional changes:
- Bail out if number is > UINT_MAX and in
Red Hat
kernel: netfilter: nf_conntrack_sip: don't use simple_strtoul
vendor_redhat·2026-06-24·CVSS 7.0
CVE-2026-52986 [MEDIUM] CWE-170 kernel: netfilter: nf_conntrack_sip: don't use simple_strtoul
kernel: netfilter: nf_conntrack_sip: don't use simple_strtoul
A flaw was found in the Linux kernel's netfilter SIP (Session Initiation Protocol) connection tracking module. This vulnerability, caused by unsafe port parsing, allows a remote attacker to send specially crafted malformed packets. Such packets could lead to excessive resource consumption, potentially resulting in a denial of service (DoS) condition. The issue is due to the use of an insecure parsing function on non-NUL-terminated data without adequate bounds checks.
Package: kernel (Red Hat Enterprise Linux 10) - Affected
Package: kernel (Red Hat Enterprise Linux 6) - Out of support scope
Package: kernel (Red Hat Enterprise Linux 7) - Affected
Package: kernel-rt (Red Hat Enterprise Linux 7) - Affected
Package: kernel (Red
No detection rules found.
No public exploits indexed.
https://git.kernel.org/stable/c/523762e3b6933fff81f01dfa3c60c0774044cdabhttps://git.kernel.org/stable/c/7df9863bf538a626e8a684e59cb2c43eac0ef3c8https://git.kernel.org/stable/c/8cd0358379570003659186706e077929d6930c40https://git.kernel.org/stable/c/8cf6809cddcbe301aedfc6b51bcd4944d45795f6https://git.kernel.org/stable/c/9c6afcb1c3cbb2c0da65b8515ac14d7273872f84https://git.kernel.org/stable/c/9f69c323ae0ab517e595c2cc74e0ae0d9d085611https://git.kernel.org/stable/c/b3264c977e79d8a25778d4fd11520f00fea1329chttps://git.kernel.org/stable/c/ea2ecd29b8f4433e52607192ca91084f95787ca0
2026-06-24
Published