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Vulnerability record · CVE-2026-23457 · published 3 April 2026

CVE-2026-23457: Linux kernel vulnerability

Linux · Linux Kernel

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_sip: fix Content-Length u32 truncation in sip_help_tcp() sip_help_tcp() parses the SIP Content-Length header with simple_strtoul(), which returns unsigned long, but stores the result in unsigned int clen. On 64-bit systems, values exceeding UINT_MAX are silently truncated before computing the SIP message boundary. For example, Content-Length 4294967328 (2^32 + 32) is truncated to 32, causing the parser to miscalculate where the current message ends. The loop then treats trailing data in the TCP segment as a second SIP message and processes it through the SDP parser. Fix this by changing clen to unsigned long to match the return type of simple_strtoul(), and reject Content-Length values that exceed the remaining TCP payload length.

8.6 CVSS 3.1 High EPSS 0.43% · top 64.9%
8.6CVSS 3.1 base score
0.43%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
10References
24 Jul 2026Last modified by NVD

Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_sip: fix Content-Length u32 truncation in sip_help_tcp() sip_help_tcp() parses the SIP Content-Length header with simple_strtoul(), which returns unsigned long, but stores the result in unsigned int clen. On 64-bit systems, values exceeding UINT_MAX are silently truncated before computing the SIP message boundary. For example, Content-Length 4294967328 (2^32 + 32) is truncated to 32, causing the parser to miscalculate where the current message ends. The loop then treats trailing data in the TCP segment as a second SIP message and processes it through the SDP parser. Fix this by changing clen to unsigned long to match the return type of simple_strtoul(), and reject Content-Length values that exceed the remaining TCP payload length.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://git.kernel.org/stable/c/528b4509c9dfc272e2e92d811915e5211650d383 Patch
https://git.kernel.org/stable/c/75fcaee5170e7dbbee778927134ef2e9568b4659 Patch
https://git.kernel.org/stable/c/865dba58958c3a86786f89a501971ab0e3ec6ba9 Patch
https://git.kernel.org/stable/c/b75209debb9adab287b3caa982f77788c1e15027 Patch
https://git.kernel.org/stable/c/cd1b7403ec835f8a0b3f1f7e68ac26af2cb1e42f Patch
https://git.kernel.org/stable/c/d4f17256544cc37f6534a14a27a9dec3540c2015 Patch
https://git.kernel.org/stable/c/ed81b6a7012485acdb9c6c80735a0b7d8e5e1873 Patch
https://git.kernel.org/stable/c/fbce58e719a17aa215c724473fd5baaa4a8dc57c Patch
https://cert-portal.siemens.com/productcert/html/ssa-019113.html
https://cert-portal.siemens.com/productcert/html/ssa-082556.html

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Source: NIST National Vulnerability Database (record CVE-2026-23457), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.