{"answers":{"affected":"It affects 1 product.","exploited":"There is no known exploitation of CVE-2026-39860 in the wild and no public exploit code.","fix":"Upgrade to a fixed version.","what":"CVE-2026-39860 is a critical path traversal vulnerability in NixOS nix, published on 8 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim."},"fix_prompt":"Check this codebase for CVE-2026-39860 and fix it if it is affected.\n\nWhat it is: CVE-2026-39860 is a critical path traversal vulnerability in NixOS nix, published on 8 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.\nExploitation: There is no known exploitation of CVE-2026-39860 in the wild and no public exploit code.\n\nAffected product: NixOS nix. No package-level version data is available, so check the vendor advisory linked from the reference page.\n\nTask:\n1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.\n2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.\n3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.\n4. Run the tests and summarise what changed and why.\n5. If nothing in the project is affected, say so and change nothing.\n\nReference: https://insights.sbomify.com/CVE-2026-39860/ (Markdown: https://insights.sbomify.com/CVE-2026-39860/index.md)","id":"CVE-2026-39860","markdown":"https://insights.sbomify.com/CVE-2026-39860/index.md","name":"CVE-2026-39860","record":{"aliases":["DEBIAN-CVE-2026-39860","GHSA-g3g9-5vj6-r3gj","UBUNTU-CVE-2026-39860"],"analysis":{"component_type":"operating_system","fix_type":"upgrade","impacts":["privilege_escalation","code_execution"],"network_reachable":"adjacent_or_local","non_default_config":false,"product_category":"Nix package manager","requires_auth":"none","summary":"A symlink vulnerability in Nix allows attackers to overwrite arbitrary files as root, leading to privilege escalation in multi-user installations.","user_interaction":"not_required","vuln_class":"path_traversal"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"GitHub_M","cpe":[{"product":"nix","vendor":"nixos"}],"cvss":{"score":9,"severity":"critical","source":"cna","vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N","version":"3.1"},"cwes":[{"id":"CWE-61","name":"UNIX Symbolic Link (Symlink) Following"}],"description":"Nix is a package manager for Linux and other Unix systems. A bug in the fix for CVE-2024-27297 allowed for arbitrary overwrites of files writable by the Nix process orchestrating the builds (typically the Nix daemon running as root in multi-user installations) by following symlinks during fixed-output derivation output registration. This affects sandboxed Linux builds - sandboxed macOS builds are unaffected. The location of the temporary output used for the output copy was located inside the build chroot. A symlink, pointing to an arbitrary location in the filesystem, could be created by the derivation builder at that path. During output registration, the Nix process (running in the host mount namespace) would follow that symlink and overwrite the destination with the derivation's output contents. In multi-user installations, this allows all users able to submit builds to the Nix daemon (allowed-users - defaulting to all users) to gain root privileges by modifying sensitive files. This vulnerability is fixed in 2.34.5, 2.33.4, 2.32.7, 2.31.4, 2.30.4, 2.29.3, and 2.28.6.","ecosystems":[],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"none_known"},"has_fix":true,"headline":"Nix sandbox escape: file write via symlink at FOD `.tmp` copy destination","id":"CVE-2026-39860","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":null,"products":[],"type":"path_traversal","year":"2026"},"n_packages":0,"n_references":6,"next":{"headline":"Claude Code: Sandbox Escape via Symlink Following Allows Arbitrary File Write Outside Workspace","id":"CVE-2026-39861"},"packages":[],"prev":{"headline":"LiquidJS has a renderFile() / parseFile() bypass configured root and allow arbitrary file read","id":"CVE-2026-39859"},"products":["nix"],"published":"2026-04-08","related":[{"cvss_score":9.1,"headline":"Nix affected by unsafe NAR unpacking","id":"CVE-2024-45593","kev_date_added":null,"published":"2024-09-10"},{"cvss_score":7.8,"headline":"Misconfiguration in n/a","id":"CVE-2019-17365","kev_date_added":null,"published":"2019-10-09"},{"cvss_score":6.3,"headline":"Nix Corruption of fixed-output derivations","id":"CVE-2024-27297","kev_date_added":null,"published":"2024-03-11"}],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"US public information, NVD API terms","name":"NVD"},{"class":"attribution","licence":"CWE Terms of Use","name":"CWE (MITRE)"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":"no","exploitation":"none","technical_impact":"total"},"state":"PUBLISHED","updated":"2026-04-09","vendors":["NixOS"]},"summary":"A symlink vulnerability in Nix allows attackers to overwrite arbitrary files as root, leading to privilege escalation in multi-user installations.","url":"https://insights.sbomify.com/CVE-2026-39860/"}