CyberSecBulletin
CVE-2026-44028NVD status: Deferred

Nix: Uncontrolled Recursion

Published Updated By the CyberSecBulletin desk

CVE-2026-44028 is a high-severity uncontrolled recursion vulnerability in Nix from NixOS, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions 2.28.7, 2.29.4, 2.30.5 as the first without the flaw, so updating Nix to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.18% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Nix to 2.28.7 or 2.29.4 or 2.30.5 or 2.31.5, whichever matches your release line, or a later version.
  2. Update Lix to 2.93.4 or 2.94.2 or 2.95.2, whichever matches your release line, or a later version.
  3. Read the advisory on discourse.nixos.org for workarounds and exact fixed builds.

Affected products and versions

VendorProductAffected versionsFixed in
NixOSNix2.24.4 up to, but not including, 2.28.7; 2.29.0 up to, but not including, 2.29.4; 2.30.0 up to, but not including, 2.30.5; 2.31.0 up to, but not including, 2.31.5; 2.32.0 up to, but not including, 2.32.8; 2.33.0 up to, but not including, 2.33.6; 2.34.0 up to, but not including, 2.34.72.28.7, 2.29.4, 2.30.5, 2.31.5, 2.32.8, 2.33.6
Lix ProjectLix2.93.0 up to, but not including, 2.93.4; 2.94.0 up to, but not including, 2.94.2; 2.95.0 up to, but not including, 2.95.22.93.4, 2.94.2, 2.95.2

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
HighSuccess depends on conditions outside the attacker's control.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
ChangedThe attack can reach beyond the vulnerable component into other systems.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
NoneAvailability is not affected.

Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N. Scored by CNA (mitre.org).

Official 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).

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Uncontrolled Recursion

The product does not properly control the amount of recursion that takes place, consuming excessive resources, such as allocated memory or the program stack.

How developers prevent this class of flaw

  • Ensure that an end condition will be reached under all logic conditions. The end condition may include checking against the depth of recursion and exiting with an error if the recursion goes too deep. The complexity of the end condition contributes to the effectiveness of this action.

More Uncontrolled Recursion vulnerabilities (CWE-674)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Other vulnerabilities in Nix

All Nix vulnerabilities

Recent Uncontrolled Recursion vulnerabilities

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