CVE-2026-44028
CVE-2026-44028 is a high-severity vulnerability with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-674.
Key facts
- Severity: High (CVSS 3.x base score 7.5)
- EPSS exploit prediction: 0% (8th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2026-27163
- Weakness: CWE-674
- Published:
- Last modified:
Description
An issue was discovered in Nix before 2.34.7 and Lix before 2.95.2. Unbounded recursion in the NAR (Nix Archive) parser could lead to a stack-to-heap overflow when the parser is run on a coroutine stack. The stack is allocated without a guard page, which means that a stack overflow could overwrite memory on the heap and could allow arbitrary code execution as the Nix daemon (run as root in multi-user installations) if ASLR hardening is bypassed. This can be exploited by all users able to connect to the daemon (e.g., in Nix, this is configurable via the allowed-users setting, defaulting to all users). The fixed versions are 2.34.7, 2.33.6, 2.32.8, 2.31.5, 2.30.5, 2.29.4, and 2.28.7 for Nix (introduced in 2.24.4); and 2.95.2, 2.94.2, and 2.93.4 for Lix (introduced in 2.93.0).
Frequently asked questions
- What is CVE-2026-44028?
- An issue was discovered in Nix before 2.34.7 and Lix before 2.95.2. Unbounded recursion in the NAR (Nix Archive) parser could lead to a stack-to-heap overflow when the parser is run on a coroutine stack. The stack is allocated without a guard page, which means that a stack overflow could overwrite memory on the heap and could allow arbitrary code execution as the Nix daemon (run as root in multi-user installations) if ASLR hardening is bypassed. This can be exploited by all users able to connect to the daemon (e.g., in Nix, this is configurable via the allowed-users setting, defaulting to all users). The fixed versions are 2.34.7, 2.33.6, 2.32.8, 2.31.5, 2.30.5, 2.29.4, and 2.28.7 for Nix (introduced in 2.24.4); and 2.95.2, 2.94.2, and 2.93.4 for Lix (introduced in 2.93.0).
- How severe is CVE-2026-44028?
- CVE-2026-44028 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over local access with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.
- Is CVE-2026-44028 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (8th percentile), an estimate of the probability of exploitation in the next 30 days.
- How do I fix CVE-2026-44028?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
- Does CVE-2026-44028 have an EU (EUVD) identifier?
- Yes. CVE-2026-44028 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-27163.
- When was CVE-2026-44028 published?
- CVE-2026-44028 was published on 2026-05-05 and last updated on 2026-06-17.
References
- https://discourse.nixos.org/t/security-advisory-local-privilege-escalation-in-lix-and-nix/77407
- https://github.com/NixOS/nix/security/advisories/GHSA-vh5x-56v6-4368
- https://lix.systems/blog/2026-05-05-lix-unsigned-integer-overflow/
- https://www.openwall.com/lists/oss-security/2026/05/04/32
- https://www.openwall.com/lists/oss-security/2026/05/04/33
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