CVE-2026-23457

High

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.

SeverityHigh
CVSS8.6
Exploit probability—
ProductLinux Kernel
PublishedApr 3, 2026
First seenApr 3, 2026

How to fix

Update
  • linux linux_kernel5.10.253, 5.15.203, 6.1.167, 6.6.130, 6.12.78, 6.18.20, 6.19.10 or later

Affected products

ProductAffected versionsFixed in
linux linux_kernel2.6.34 ≤ v < 5.10.253, 5.11 ≤ v < 5.15.203, 5.16 ≤ v < 6.1.167, 6.2 ≤ v < 6.6.130, 6.7 ≤ v < 6.12.78, 6.13 ≤ v < 6.18.20, 6.19 ≤ v < 6.19.10, 7.05.10.253, 5.15.203, 6.1.167, 6.6.130, 6.12.78, 6.18.20, 6.19.10

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