CVE-2026-23457

Summary

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.

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/ed81b6a7012485acdb9c6c80735a0b7d8e5e1873
• https://git.kernel.org/stable/c/cd1b7403ec835f8a0b3f1f7e68ac26af2cb1e42f
• https://git.kernel.org/stable/c/b75209debb9adab287b3caa982f77788c1e15027
• https://git.kernel.org/stable/c/528b4509c9dfc272e2e92d811915e5211650d383
• https://git.kernel.org/stable/c/75fcaee5170e7dbbee778927134ef2e9568b4659
• https://git.kernel.org/stable/c/865dba58958c3a86786f89a501971ab0e3ec6ba9
• https://git.kernel.org/stable/c/d4f17256544cc37f6534a14a27a9dec3540c2015
• https://git.kernel.org/stable/c/fbce58e719a17aa215c724473fd5baaa4a8dc57c

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