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VulnerabilityPublished

CVE-2026-25740: NixOS nixpkgs · Execution with Unnecessary Privileges

Affects NixOS nixpkgsSource CVE Database V5

0

Not known to be exploited · CVSS 5.8 Medium · fixed in 25.11 : update NixOS nixpkgs when convenient.

Data as of 26 Oct 2026, 17:16 UTC

CVSS 4.0 base score
5.8Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 5% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 25.11
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

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 9 Feb 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Affected software

ProductAffectedFixed in
NixOSnixpkgsAffected
  • <=25.05
Fixed in–

AI-suggested

European organizations should immediately upgrade NixOS installations to versions 25.11 or later, where the vulnerability is patched. If upgrading is not immediately feasible, administrators should disable the captive-browser feature to eliminate the attack vector. Restrict captive-browser usage to trusted, minimal-privilege users and enforce strict access controls on systems running this feature. Employ Linux security modules such as SELinux or AppArmor to confine the captive-browser process and limit its capabilities, particularly restricting CAP_NET_RAW. Regularly audit user privileges and monitor for unusual network activity indicative of spoofing or unauthorized binding to privileged ports. Implement network segmentation to isolate critical services from potentially compromised hosts. Additionally, maintain up-to-date intrusion detection systems to detect anomalous network behaviors that could result from exploitation attempts. Finally, educate users about the risks of local privilege escalation and enforce strong authentication and endpoint security policies to reduce the likelihood of initial compromise.

Description

CVE-2026-25740 is a medium-severity vulnerability in NixOS nixpkgs versions 25.05 and earlier, involving the captive-browser feature. This feature runs a dedicated Chrome instance to handle captive portal logins without altering DNS settings. When enabled, any local user can execute arbitrary commands with the CAP_NET_RAW capability, allowing actions such as binding to privileged ports and spoofing localhost traffic from privileged services. The vulnerability arises from execution with unnecessary privileges (CWE-250). It requires local access and partial privileges but no user interaction. The issue is fixed in versions 25.11 and 26.05. Although no known exploits are reported in the wild, the potential for privilege escalation and network spoofing poses risks, especially in multi-user environments.

References

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