Privilege escalation to the `CAP_NET_RAW` capability via the `programs.captive-browser` NixOS module

published 2026-02-09 8 mo ago modified 2026-06-17 4 mo ago also EUVD-2026-6848

cvss: 5.8; version 4.0, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 5%
public exploits: 0; none known

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.

Patch / fix

links 2

github.com/NixOS/nixpkgs#487775 pull request
github.com/NixOS/nixpkgs#487779 pull request

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 8 mo ago (2026-02-10)

Exploit prediction

0.16% chance of exploitation in the next 30 days, higher than 5% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	4.0	5.8	CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N
CNA	4.0	5.8	CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected products

NixOS nixpkgs

Classification

Weakness

CWE-250 Execution with Unnecessary Privileges

References

Sources

CVE List CVE-2026-25740
NVD CVE-2026-25740

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary