EUVD-2026-18714Lifecycle Timeline
3Description
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.
Analysis
Integer truncation in Linux kernel netfilter SIP helper allows remote attackers to bypass Content-Length validation and cause information disclosure via malformed SIP messages. The sip_help_tcp() function stores SIP Content-Length header values (returned as unsigned long) into an unsigned int variable, causing values exceeding UINT_MAX (4,294,967,295) to truncate silently on 64-bit systems. …
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