CVE-2026-100070 netfilter: nf_nat_sip: rewind offset when NAT shrinks the packet

What is CVE-2026-100070?

CVE-2026-100070 is a medium-severity vulnerability in Linux kernel, published on 25 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.

Official 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?

Which versions are affected by CVE-2026-100070?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2026-100070?

Apply the vendor's patch.

Is CVE-2026-100070 being exploited?

There is no known exploitation of CVE-2026-100070 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BELL-CVE-2026-100070, DEBIAN-CVE-2026-100070, GHSA-hw8v-4xhx-cmhp, UBUNTU-CVE-2026-100070.