{"answers":{"affected":"It affects 2 products.","exploited":"Yes. Attackers have exploited CVE-2020-6820 in the wild since at least 3 Nov 2021.","fix":"Upgrade to a fixed version. US federal agencies must fix it by 3 May 2022.","what":"CVE-2020-6820 is a high-severity use after free vulnerability in Mozilla Firefox, published on 24 Apr 2020. An attacker can exploit it over the internet without logging in, with no action from the victim."},"fix_prompt":"Check this codebase for CVE-2020-6820 and fix it if it is affected.\n\nWhat it is: CVE-2020-6820 is a high-severity use after free vulnerability in Mozilla Firefox, published on 24 Apr 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.\nExploitation: Yes. Attackers have exploited CVE-2020-6820 in the wild since at least 3 Nov 2021.\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-2020-6820/ (Markdown: https://insights.sbomify.com/CVE-2020-6820/index.md)","id":"CVE-2020-6820","markdown":"https://insights.sbomify.com/CVE-2020-6820/index.md","name":"CVE-2020-6820","record":{"aliases":["DEBIAN-CVE-2020-6820","GHSA-f77r-rqc9-53hh","UBUNTU-CVE-2020-6820"],"analysis":{"component_type":"browser","fix_type":"upgrade","impacts":["code_execution"],"network_reachable":"yes","non_default_config":false,"product_category":"Mozilla Firefox","requires_auth":"none","summary":"A race condition in ReadableStream handling leads to a use-after-free, allowing attackers to execute arbitrary code via targeted attacks.","user_interaction":"not_required","vuln_class":"use_after_free"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"mozilla","cpe":[{"product":"firefox","vendor":"mozilla"},{"product":"thunderbird","vendor":"mozilla"}],"cvss":{"score":8.1,"severity":"high","source":"cisa-adp","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"cwes":[{"id":"CWE-362","name":"Concurrent Execution using Shared Resource with Improper Synchronization"}],"description":"Under certain conditions, when handling a ReadableStream, a race condition can cause a use-after-free. We are aware of targeted attacks in the wild abusing this flaw. This vulnerability affects Thunderbird \u003c 68.7.0, Firefox \u003c 74.0.1, and Firefox ESR \u003c 68.6.1.","ecosystems":[],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"exploited"},"has_fix":true,"headline":"Mozilla Firefox And Thunderbird Use-After-Free","id":"CVE-2020-6820","indexable":true,"kev":{"dateAdded":"2021-11-03","dueDate":"2022-05-03","knownRansomwareCampaignUse":"Unknown","product":"Firefox and Thunderbird","requiredAction":"Apply updates per vendor instructions.","vendorProject":"Mozilla","vulnerabilityName":"Mozilla Firefox And Thunderbird Use-After-Free Vulnerability"},"kind":"cve","links":{"ecosystem":null,"product":"mozilla:firefox","products":["mozilla:firefox","mozilla:thunderbird"],"type":"use_after_free","year":"2020"},"n_packages":0,"n_references":4,"next":{"headline":"Information disclosure in Firefox","id":"CVE-2020-6821"},"packages":[],"prev":{"headline":"Mozilla Firefox And Thunderbird Use-After-Free","id":"CVE-2020-6819"},"products":["Firefox","Firefox ESR","Thunderbird"],"published":"2020-04-24","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"}],"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":"open","licence":"CC0 1.0","name":"CISA KEV"},{"class":"attribution","licence":"CWE Terms of Use","name":"CWE (MITRE)"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":"no","exploitation":"active","technical_impact":"total"},"state":"PUBLISHED","updated":"2025-10-21","vendors":["Mozilla"]},"summary":"A race condition in ReadableStream handling leads to a use-after-free, allowing attackers to execute arbitrary code via targeted attacks.","url":"https://insights.sbomify.com/CVE-2020-6820/"}