CVE-2026-25740: Privilege escalation to the `CAP_NET_RAW` capability via the `programs.captive-browser` NixOS module

Severity: medium (CVSS 5.8 v4.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-02-09 · updated 2026-06-17
Weakness: CWE-250

Description

captive browser, a dedicated Chrome instance to log into captive portals without messing with DNS settings. In 25.05 and earlier, when programs.captive-browser is enabled, any user of the system can run arbitrary commands with the CAP_NET_RAW capability (binding to privileged ports, spoofing localhost traffic from privileged services...). This vulnerability is fixed in 25.11 and 26.05.

Affected products

NixOS nixpkgs: through 25.05

References

https://github.com/NixOS/nixpkgs/pull/487775
https://github.com/NixOS/nixpkgs/pull/487779
https://github.com/NixOS/nixpkgs/security/advisories/GHSA-wc3r-c66x-8xmc

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