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Fencer Intel
low 2.8

CVE-2026-64846 json

Nix: Arbitrary file truncation outside the sandbox with recursive-nix experimental feature

published 3mo ago modified 24d ago also EUVD-2026-63424 , GHSA-6h4g-g5j9-fm5f

Unreviewed: the maintainers' own advisory

Published by the maintainers on their GitHub repository NixOS/nix. GitHub has not reviewed it into the GitHub Advisory Database, so the affected packages and versions are the maintainers' word. Read the full advisory on GitHub.

cvss
2.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 1%
public exploits
0
none known

Summary

Nix is a package manager for Linux and other Unix systems. Prior to 2.35.0, a malicious derivation executed with the recursive-nix experimental feature can exploit a time-of-check/time-of-use race involving final symlink handling in the LocalStore restore path. The race can cause writeFile to follow a substituted final symlink when opening a path with O_TRUNC instead of enforcing FinalSymlink::DontFollow, allowing the Nix process or nix-daemon to create or truncate an empty file outside the build sandbox with the daemon user's permissions. The primitive does not provide arbitrary-content writes and requires winning the race. This issue is fixed in version 2.35.0.

Patch / fix

  • nixos nix 2.35.0
  • nix Debian 14 2.35.4+dfsg-1

debian advisories DEBIAN-CVE-2026-64846

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-64846 updated cvss 2.8

nix: Nix: Arbitrary file truncation via time-of-check/time-of-use race

  • Red Hat Ansible Automation Orchestrator 2026 ansible-automation-platform/automation-orchestrator-backend-rhel9 Red Hat Confidential Compute Attestation build-of-trustee/trustee-rhel9, agent-sandbox/agent-sandbox-router, openshift-sandboxed-containers/osc-podvm-builder-rhel9, openshift-sandboxed-containers/osc-podvm-payload-rhel9 Red Hat Logging Subsystem for Red Hat OpenShift openshift-logging/vector-rhel9 Red Hat OpenShift Lightspeed openshift-lightspeed/lightspeed-ocp-rag-rhel9, openshift-lightspeed-tech-preview/lightspeed-rag-tool-rhel9, openshift-lightspeed/lightspeed-to-dataverse-exporter-rhel9 Red Hat OpenShift Service Mesh 3 openshift-service-mesh/istio-ztunnel-rhel9 Red Hat Pen Drive Powered by Red Hat Lightspeed pen-drive/pen-drive-scanner-rhel9
    +15 more products
    Red Hat Ansible Automation Platform 2 ansible-automation-platform-26/hub-rhel9, ansible-automation-platform-27/hub-rhel9, ansible-automation-platform-26/gateway-rhel9, ansible-automation-platform-27/gateway-rhel9, ansible-automation-platform-26/mcp-tools-rhel9, ansible-automation-platform-27/mcp-tools-rhel9, +15 more Red Hat Ansible Automation Platform Ansible Core 2 ansible-automation-platform/ee-minimal-rhel8, ansible-automation-platform/ee-minimal-rhel9, ansible-automation-platform-tech-preview/ee-minimal-rhel8, ansible-automation-platform-tech-preview/ee-minimal-rhel9 Red Hat Discovery 2 discovery/discovery-server-rhel9 Red Hat Enterprise Linux 7 firefox Red Hat Enterprise Linux 8 rls, rust, cargo, clippy, nispor, firefox, +18 more Red Hat Enterprise Linux 9 rust, bootc, cargo, goose, clippy, nispor, +39 more Red Hat Enterprise Linux 10 rust, bootc, goose, loupe, papers, firefox, +20 more Red Hat Enterprise Linux AI (RHEL AI) 3 rust Red Hat Enterprise Linux command line assistant rhel-cla/rhel-knowledge-bridge-rhel10 Red Hat OpenShift AI (RHOAI) rhoai/odh-feature-server-rhel9, rhai/base-image-torch-2.14-cpu-rhel9, rhoai/odh-llm-d-inference-scheduler-rhel9, rhai/base-image-torch-2.14-cuda-13.0-rhel9, rhoai/odh-model-registry-job-async-upload-rhel9 Red Hat OpenShift Container Platform 4 bootupd, afterburn, conmon-rs, rpm-ostree, rust-bootupd, rust-afterburn, +6 more Red Hat OpenShift Container Platform 5 conmon-rs, kata-containers Red Hat Quay 3 quay/quay-rhel8, quay/quay-rhel9 Red Hat Satellite 6 satellite/iop-vmaas-rhel9, satellite/iop-advisor-engine-rhel9, satellite/iop-advisor-backend-rhel9 Red Hat Trusted Profile Analyzer rhtpa/rhtpa-rhel10, rhtpa/rhtpa-trustification-service-rhel9
    affected: workaround, no fix available “Fix deferred”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
2mo ago

Exploit prediction

0.11% chance of exploitation in the next 30 days, higher than 1% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 3.1 2.8 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:N/I:L/A:N

Affected products

  • NixOS nix

Classification

Weakness
  • CWE-61 UNIX Symbolic Link (Symlink) Following
  • CWE-367 Time-of-check Time-of-use (TOCTOU) Race Condition

References

Sources

Fencer Intel 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.

The maintainers of NixOS/nix published their own advisory on GitHub. Reviewed sources take precedence over it.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.