{"answers":{"affected":"It affects 1 product.","exploited":"It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-73253 exists.","fix":"Upgrade to a fixed version.","what":"CVE-2026-73253 is a critical vulnerability in Cesanta Mongoose, published on 20 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim."},"fix_prompt":"Check this codebase for CVE-2026-73253 and fix it if it is affected.\n\nWhat it is: CVE-2026-73253 is a critical vulnerability in Cesanta Mongoose, published on 20 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.\nExploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-73253 exists.\n\nAffected product: Cesanta Mongoose. 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-2026-73253/ (Markdown: https://insights.sbomify.com/CVE-2026-73253/index.md)","id":"CVE-2026-73253","markdown":"https://insights.sbomify.com/CVE-2026-73253/index.md","name":"CVE-2026-73253","record":{"aliases":["DEBIAN-CVE-2026-73253","GHSA-jp6g-796f-39vp","JLSEC-2026-1377","UBUNTU-CVE-2026-73253"],"analysis":{"component_type":"library","fix_type":"upgrade","impacts":["data_read","data_modify"],"network_reachable":"yes","non_default_config":false,"product_category":"Mongoose embedded web server","requires_auth":"none","summary":"An on-path attacker can bypass TLS hostname verification in Mongoose to intercept and modify traffic using a wildcard certificate.","user_interaction":"not_required","vuln_class":"security_feature_bypass"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"GitHub_M","cpe":[{"product":"mongoose","vendor":"cesanta"}],"cvss":{"score":9.1,"severity":"critical","source":"cna","vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N","version":"4.0"},"cwes":[{"id":"CWE-295","name":"Improper Certificate Validation"}],"description":"Mongoose is an embedded web server and network library. Prior to version 7.22, an on-path network attacker with a wildcard certificate for a parent domain can impersonate deeper subdomains to a client using the built-in TLS stack. The mg_tls_verify_cert_san() and mg_tls_verify_cert_cn() functions in src/tls_builtin.c call mg_match(), whose wildcard can cross DNS label boundaries, so a pattern such as *.example.com can match foo.bar.example.com. The resulting hostname verification bypass permits interception and modification of TLS traffic. This issue is fixed in version 7.22.","ecosystems":[],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"weaponised"},"has_fix":true,"headline":"Mongoose: TLS Hostname Verification Bypass via Overly Permissive Wildcard Matching","id":"CVE-2026-73253","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":"cesanta:mongoose","products":["cesanta:mongoose"],"type":"security_feature_bypass","year":"2026"},"n_packages":0,"n_references":4,"next":{"headline":"Mongoose: Stored XSS via unescaped filenames in directory listing","id":"CVE-2026-73254"},"packages":[],"prev":{"headline":"Memory corruption in mongoose","id":"CVE-2026-73252"},"products":["mongoose"],"published":"2026-08-20","related":[{"cvss_score":9.8,"headline":"Arbitrary File Write","id":"CVE-2022-25299","kev_date_added":null,"published":"2022-02-18"},{"cvss_score":9.8,"headline":"Memory corruption in n/a","id":"CVE-2020-25756","kev_date_added":null,"published":"2020-09-18"},{"cvss_score":9.8,"headline":"Integer overflow in n/a","id":"CVE-2019-19307","kev_date_added":null,"published":"2019-11-26"},{"cvss_score":9.8,"headline":"Memory corruption in n/a","id":"CVE-2019-12951","kev_date_added":null,"published":"2019-06-24"},{"cvss_score":9.8,"headline":"Use after free in n/a","id":"CVE-2018-20353","kev_date_added":null,"published":"2019-06-10"},{"cvss_score":9.8,"headline":"Use after free in n/a","id":"CVE-2018-20354","kev_date_added":null,"published":"2019-06-10"},{"cvss_score":9.8,"headline":"Use after free in n/a","id":"CVE-2018-20355","kev_date_added":null,"published":"2019-06-10"}],"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":"poc","technical_impact":"total"},"state":"PUBLISHED","updated":"2026-08-20","vendors":["cesanta"]},"summary":"An on-path attacker can bypass TLS hostname verification in Mongoose to intercept and modify traffic using a wildcard certificate.","url":"https://insights.sbomify.com/CVE-2026-73253/"}