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?

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Fri, 25 Sep 2026 13:30:00 +0000

Type Values Removed Values Added
Description 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?
Title netfilter: nf_nat_sip: rewind offset when NAT shrinks the packet
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
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cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-09-25T13:06:44.311Z

Reserved: 2026-09-25T10:25:14.456Z

Link: CVE-2026-100070

cve-icon Vulnrichment

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cve-icon NVD

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cve-icon Redhat

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cve-icon OpenCVE Enrichment

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