ipv4: restrict IPOPT_SSRR and IPOPT_LSRR options
In the Linux kernel, the following vulnerability has been resolved: ipv4: restrict IPOPT_SSRR and IPOPT_LSRR options This patch restricts setting Loose Source and Record Route (LSRR) and Strict Source and Record Route (SSRR) IP options to users with CAP_NET_RAW capability. This prevents unprivileged applications from forcing packets to route through attacker-controlled nodes to leak TCP ISN and possibly other protocol information. While LSRR and SSRR are commonly filtered in many network environments, they may still be supported and forwarded along some network paths. RFC 7126 (Recommendations on Filtering of IPv4 Packets Containing IPv4 Options) recommend to drop these options in 4.3 and 4.4.
02 / AFFECTED SOFTWARE
Affected packages
1837 explicit affected versions
03 / CONNECTIONS
Connected vulnerabilities
04 / EVIDENCE
Source records
In the Linux kernel, the following vulnerability has been resolved: ipv4: restrict IPOPT_SSRR and IPOPT_LSRR options This patch restricts setting Loose Source and Record Route (LSRR) and Strict Source and Record Route (SSRR) IP options to users with CAP_NET_RAW capability. This prevents unprivileged applications from forcing packets to route through attacker-controlled nodes to leak TCP ISN and possibly other protocol information. While LSRR and SSRR are commonly filtered in many network environments, they may still be supported and forwarded along some network paths. RFC 7126 (Recommendations on Filtering of IPv4 Packets Containing IPv4 Options) recommend to drop these options in 4.3 and 4.4.
05 / REFERENCES
Further evidence
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- https://git.kernel.org/stable/c/00e8845fe3428c69e980dce5071cb3da1d8f7578
- https://git.kernel.org/stable/c/28f5ad1b4055405eb1616e603fe511ba5e3725e7
- https://git.kernel.org/stable/c/2a87c3e8f03ce655ed0ef500d64d5fd924ec3691
- https://git.kernel.org/stable/c/4cd6e9ed49347d3a2fdaaf07e32fb524756dddc2
- https://git.kernel.org/stable/c/89343ff12b3178fc236fe531a3603e7c97c68278
- https://git.kernel.org/stable/c/8ff85dbabbbfb05e86e6cde31d91ac5782179d4d
- https://git.kernel.org/stable/c/a4f3fd6516920988c47ba8d19714985c40c816a1
- https://git.kernel.org/stable/c/d3915a1f5a4bc0ac911032903c3c6ab8df9fcc7c
- https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53249.json
- https://nvd.nist.gov/vuln/detail/CVE-2026-53249