{"answers":{"affected":"3 open source packages ship an affected version, including github.com/quic-go/webtransport-go. It affects 1 product.","exploited":"There is no known exploitation of CVE-2026-21435 in the wild and no public exploit code.","fix":"Upgrade github.com/quic-go/webtransport-go to 0.10.0 or later.","what":"CVE-2026-21435 is a medium-severity vulnerability in quic-go webtransport-go, published on 12 Feb 2026."},"fix_prompt":"Check this codebase for CVE-2026-21435 and fix it if it is affected.\n\nWhat it is: CVE-2026-21435 is a medium-severity vulnerability in quic-go webtransport-go, published on 12 Feb 2026. \nExploitation: There is no known exploitation of CVE-2026-21435 in the wild and no public exploit code.\n\nAffected packages and fixed versions:\n- github.com/quic-go/webtransport-go (Go): affected all versions; fixed in 0.10.0\n- github.com/quic-go/webtransport-go (Go): affected all versions; fixed in 0.10.0\n- github.com/quic-go/webtransport-go (Go): affected all versions; fixed in 0.10.0\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-2026-21435/ (Markdown: https://insights.sbomify.com/CVE-2026-21435/index.md)","id":"CVE-2026-21435","markdown":"https://insights.sbomify.com/CVE-2026-21435/index.md","name":"CVE-2026-21435","record":{"aliases":["GHSA-px4r-g4p3-hhqv","GO-2026-4488","MINI-7v4c-m83q-mv84","MINI-j8jp-fhv4-h367"],"analysis":null,"analysis_generated_by":null,"assigner":"GitHub_M","cpe":[{"product":"webtransport-go","vendor":"quic-go"}],"cvss":{"score":5.3,"severity":"medium","source":"cna","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","version":"3.1"},"cwes":[{"id":"CWE-400","name":"Uncontrolled Resource Consumption"}],"description":"webtransport-go is an implementation of the WebTransport protocol. Prior to v0.10.0, an attacker can cause a denial of service in webtransport-go by preventing or indefinitely delaying WebTransport session closure. A malicious peer can withhold QUIC flow control credit on the CONNECT stream, blocking transmission of the WT_CLOSE_SESSION capsule and causing the close operation to hang. This vulnerability is fixed in v0.10.0.","ecosystems":["Go"],"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":"webtransport-go CloseWithError can block indefinitely","id":"CVE-2026-21435","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":"Go","product":null,"products":[],"type":null,"year":"2026"},"n_packages":3,"n_references":2,"next":{"headline":"eopkg has Path Traversal: '../filedir' vulnerability","id":"CVE-2026-21436"},"packages":[{"ecosystem":"Go","fixed":["0.10.0"],"introduced":["0"],"last_affected":[],"package":"github.com/quic-go/webtransport-go","purl":null,"source":"GHSA-px4r-g4p3-hhqv"},{"ecosystem":"Go","fixed":["0.10.0"],"introduced":["0"],"last_affected":[],"package":"github.com/quic-go/webtransport-go","purl":"pkg:golang/github.com/quic-go/webtransport-go","source":"GHSA-px4r-g4p3-hhqv"},{"ecosystem":"Go","fixed":["0.10.0"],"introduced":["0"],"last_affected":[],"package":"github.com/quic-go/webtransport-go","purl":"pkg:golang/github.com/quic-go/webtransport-go","source":"GO-2026-4488"}],"prev":{"headline":"webtransport-go affected by Memory Exhaustion Attack due to Missing Length Check in WT_CLOSE_SESSION Capsule","id":"CVE-2026-21434"},"products":["webtransport-go"],"published":"2026-02-12","related":[{"cvss_score":5.3,"headline":"webtransport-go affected by Memory Exhaustion Attack due to Missing Length Check in WT_CLOSE_SESSION Capsule","id":"CVE-2026-21434","kev_date_added":null,"published":"2026-02-12"},{"cvss_score":5.3,"headline":"webtransport-go affected by a Memory Exhaustion Attack due to Missing Cleanup of Streams Map","id":"CVE-2026-21438","kev_date_added":null,"published":"2026-02-12"}],"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":"CC BY 4.0","name":"Go Vulnerability Database","prefix":"GO"},{"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":"yes","exploitation":"none","technical_impact":"partial"},"state":"PUBLISHED","updated":"2026-02-17","vendors":["quic-go"]},"summary":null,"url":"https://insights.sbomify.com/CVE-2026-21435/"}