netfilter: nf_nat_sip: rewind offset when NAT shrinks the packet

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_nat_sip: rewind offset when NAT shrinks the packet sashiko says: If map_addr() changes the packet length, such as when the public NAT IP string is shorter or longer than the internal IP, coff will still point to the offset relative to the pre-mangled packet. If the packet shrinks, coff could overshoot the correct position, potentially causing the next ct_sip_parse_header_uri() call to silently skip bytes and miss subsequent Contact headers. Could this lead to a failure to NAT those subsequent headers and leak internal network details?

Source published

25 Sep 2026 13:06:44 UTC

Source modified

19 Oct 2026 08:43:02 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

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