{"answers":{"affected":"It affects 2 products.","exploited":"There is no known exploitation of CVE-2026-8959 in the wild and no public exploit code.","fix":"Upgrade to a fixed version.","what":"CVE-2026-8959 is a critical vulnerability in Mozilla Firefox, published on 19 May 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link."},"fix_prompt":"Check this codebase for CVE-2026-8959 and fix it if it is affected.\n\nWhat it is: CVE-2026-8959 is a critical vulnerability in Mozilla Firefox, published on 19 May 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.\nExploitation: There is no known exploitation of CVE-2026-8959 in the wild and no public exploit code.\n\nAffected product: Mozilla Firefox. 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-2026-8959/ (Markdown: https://insights.sbomify.com/CVE-2026-8959/index.md)","id":"CVE-2026-8959","markdown":"https://insights.sbomify.com/CVE-2026-8959/index.md","name":"CVE-2026-8959","record":{"aliases":["GHSA-3x92-cxc7-h2pw","UBUNTU-CVE-2026-8959"],"analysis":{"component_type":"browser","fix_type":"upgrade","impacts":["code_execution","privilege_escalation"],"network_reachable":"yes","non_default_config":false,"product_category":"Mozilla Firefox","requires_auth":"none","summary":"Attackers can escape the browser sandbox via incorrect boundary conditions in the Win32 widget component, potentially executing arbitrary code.","user_interaction":"required","vuln_class":"security_feature_bypass"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"mozilla","cpe":[{"product":"firefox","vendor":"mozilla"},{"product":"thunderbird","vendor":"mozilla"}],"cvss":{"score":9.6,"severity":"critical","source":"cisa-adp","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H","version":"3.1"},"cwes":[{"id":"CWE-693","name":"Protection Mechanism Failure"},{"id":"CWE-20","name":"Improper Input Validation"},{"id":"CWE-119","name":"Improper Restriction of Operations within the Bounds of a Memory Buffer"}],"description":"Sandbox escape due to incorrect boundary conditions in the Widget: Win32 component. This vulnerability was fixed in Firefox 151, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.","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":"Sandbox escape due to incorrect boundary conditions in the Widget: Win32 component","id":"CVE-2026-8959","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":"mozilla:firefox","products":["mozilla:firefox","mozilla:thunderbird"],"type":"security_feature_bypass","year":"2026"},"n_packages":0,"n_references":5,"next":{"headline":"Spoofing issue in WebExtensions","id":"CVE-2026-8960"},"packages":[],"prev":{"headline":"Information disclosure, sandbox escape in the Security: Process Sandboxing component","id":"CVE-2026-8958"},"products":["Firefox","Thunderbird"],"published":"2026-05-19","related":[{"cvss_score":10,"headline":"Mozilla Firefox and Thunderbird Sandbox Escape","id":"CVE-2019-11708","kev_date_added":"2022-05-23","published":"2019-07-23"},{"cvss_score":9.8,"headline":"Mozilla Multiple Products Remote Code Execution","id":"CVE-2010-3765","kev_date_added":"2025-10-06","published":"2010-10-27"},{"cvss_score":9.6,"headline":"Mozilla Firefox Use-After-Free","id":"CVE-2022-26486","kev_date_added":"2022-03-07","published":"2022-12-22"},{"cvss_score":8.8,"headline":"Mozilla Firefox Use-After-Free","id":"CVE-2022-26485","kev_date_added":"2022-03-07","published":"2022-12-22"},{"cvss_score":8.8,"headline":"Mozilla Firefox and Thunderbird Type Confusion","id":"CVE-2019-11707","kev_date_added":"2022-05-23","published":"2019-07-23"},{"cvss_score":8.1,"headline":"Mozilla Firefox And Thunderbird Use-After-Free","id":"CVE-2020-6819","kev_date_added":"2021-11-03","published":"2020-04-24"},{"cvss_score":8.1,"headline":"Mozilla Firefox And Thunderbird Use-After-Free","id":"CVE-2020-6820","kev_date_added":"2021-11-03","published":"2020-04-24"}],"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":"2026-05-19","vendors":["Mozilla"]},"summary":"Attackers can escape the browser sandbox via incorrect boundary conditions in the Win32 widget component, potentially executing arbitrary code.","url":"https://insights.sbomify.com/CVE-2026-8959/"}