{"answers":{"affected":"2 open source packages ship an affected version, including MailKit. It affects 1 product.","exploited":"It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-41319 exists.","fix":"Upgrade MailKit to 4.16.0 or later.","what":"CVE-2026-41319 is a medium-severity vulnerability in jstedfast MailKit, published on 24 Apr 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-2026-41319 and fix it if it is affected.\n\nWhat it is: CVE-2026-41319 is a medium-severity vulnerability in jstedfast MailKit, published on 24 Apr 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: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-41319 exists.\n\nAffected packages and fixed versions:\n- MailKit (NuGet): affected all versions; fixed in 4.16.0\n- MailKit (NuGet): affected all versions; fixed in 4.16.0\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-2026-41319/ (Markdown: https://insights.sbomify.com/CVE-2026-41319/index.md)","id":"CVE-2026-41319","markdown":"https://insights.sbomify.com/CVE-2026-41319/index.md","name":"CVE-2026-41319","record":{"aliases":["GHSA-9j88-vvj5-vhgr"],"analysis":{"component_type":"library","fix_type":"upgrade","impacts":["security_bypass"],"network_reachable":"yes","non_default_config":false,"product_category":"MailKit email library","requires_auth":"none","summary":"A Man-in-the-Middle attacker can inject protocol responses during STARTTLS upgrade to force weaker SASL authentication mechanisms in MailKit.","user_interaction":"required","vuln_class":"security_feature_bypass"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"GitHub_M","cpe":[{"product":"mailkit","vendor":"jstedfast"}],"cvss":{"score":6.5,"severity":"medium","source":"cna","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N","version":"3.1"},"cwes":[{"id":"CWE-74","name":"Improper Neutralization of Special Elements in Output Used by a Downstream Component"}],"description":"MailKit is a cross-platform mail client library built on top of MimeKit. A STARTTLS Response Injection vulnerability in versions prior to 4.16.0 allows a Man-in-the-Middle attacker to inject arbitrary protocol responses across the plaintext-to-TLS trust boundary, enabling SASL authentication mechanism downgrade (e.g., forcing PLAIN instead of SCRAM-SHA-256). The internal read buffer in `SmtpStream`, `ImapStream`, and `Pop3Stream` is not flushed when the underlying stream is replaced with `SslStream` during STARTTLS upgrade, causing pre-TLS attacker-injected data to be processed as trusted post-TLS responses. Version 4.16.0 patches the issue.","ecosystems":["NuGet"],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"weaponised"},"has_fix":true,"headline":"MailKit has STARTTLS Response Injection via unflushed stream buffer that enables SASL mechanism downgrade","id":"CVE-2026-41319","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":"NuGet","product":null,"products":[],"type":"security_feature_bypass","year":"2026"},"n_packages":2,"n_references":1,"next":{"headline":"Frappe HR has possibility of SQL Injection due to improper field sanitization","id":"CVE-2026-41320"},"packages":[{"ecosystem":"NuGet","fixed":["4.16.0"],"introduced":["0"],"last_affected":[],"package":"MailKit","purl":null,"source":"GHSA-9j88-vvj5-vhgr"},{"ecosystem":"NuGet","fixed":["4.16.0"],"introduced":["0"],"last_affected":[],"package":"MailKit","purl":"pkg:nuget/MailKit","source":"GHSA-9j88-vvj5-vhgr"}],"prev":{"headline":"Cross-site scripting in anything-llm","id":"CVE-2026-41318"},"products":["MailKit"],"published":"2026-04-24","related":[],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"CC BY 4.0","name":"GitHub Advisory Database","prefix":"GHSA"},{"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":"partial"},"state":"PUBLISHED","updated":"2026-04-25","vendors":["jstedfast"]},"summary":"A Man-in-the-Middle attacker can inject protocol responses during STARTTLS upgrade to force weaker SASL authentication mechanisms in MailKit.","url":"https://insights.sbomify.com/CVE-2026-41319/"}