{"answers":{"affected":"2 open source packages ship an affected version, including github.com/vapor/leaf-kit. It affects 1 product.","exploited":"There is no known exploitation of CVE-2021-37634 in the wild and no public exploit code.","fix":"Upgrade github.com/vapor/leaf-kit to 1.3.0 or later.","what":"CVE-2021-37634 is a high-severity cross-site scripting vulnerability in vapor leaf-kit, published on 9 Aug 2021. 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-2021-37634 and fix it if it is affected.\n\nWhat it is: CVE-2021-37634 is a high-severity cross-site scripting vulnerability in vapor leaf-kit, published on 9 Aug 2021. 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-2021-37634 in the wild and no public exploit code.\n\nAffected packages and fixed versions:\n- github.com/vapor/leaf-kit (SwiftURL): affected all versions; fixed in 1.3.0\n- github.com/vapor/leaf-kit (SwiftURL): affected all versions; fixed in 1.3.0\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-2021-37634/ (Markdown: https://insights.sbomify.com/CVE-2021-37634/index.md)","id":"CVE-2021-37634","markdown":"https://insights.sbomify.com/CVE-2021-37634/index.md","name":"CVE-2021-37634","record":{"aliases":["GHSA-rv3x-xq3r-8j9h"],"analysis":{"component_type":"library","fix_type":"upgrade","impacts":["code_execution"],"network_reachable":"yes","non_default_config":false,"product_category":"Swift templating library","requires_auth":"none","summary":"Attackers can inject malicious scripts into web pages via unsanitized user input in LeafKit templates, potentially compromising user sessions.","user_interaction":"required","vuln_class":"xss"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"GitHub_M","cpe":[{"product":"leafkit","vendor":"vapor"}],"cvss":{"score":7.4,"severity":"high","source":"cna","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N","version":"3.1"},"cwes":[{"id":"CWE-79","name":"Improper Neutralization of Input During Web Page Generation"}],"description":"Leafkit is a templating language with Swift-inspired syntax. Versions prior to 1.3.0 are susceptible to Cross-site Scripting (XSS) attacks. This affects anyone passing unsanitised data to Leaf's variable tags. Before this fix, Leaf would not escape any strings passed to tags as variables. If an attacker managed to find a variable that was rendered with their unsanitised data, they could inject scripts into a generated Leaf page, which could enable XSS attacks if other mitigations such as a Content Security Policy were not enabled. This has been patched in 1.3.0. As a workaround sanitize any untrusted input before passing it to Leaf and enable a CSP to block inline script and CSS data.","ecosystems":["SwiftURL"],"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":"LeafKit allows XSS with untrusted user input","id":"CVE-2021-37634","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":"SwiftURL","product":null,"products":[],"type":"xss","year":"2021"},"n_packages":2,"n_references":2,"next":{"headline":"Heap out of bounds access in sparse reduction operations in TensorFlow","id":"CVE-2021-37635"},"packages":[{"ecosystem":"SwiftURL","fixed":["1.3.0"],"introduced":["0"],"last_affected":[],"package":"github.com/vapor/leaf-kit","purl":null,"source":"GHSA-rv3x-xq3r-8j9h"},{"ecosystem":"SwiftURL","fixed":["1.3.0"],"introduced":["0"],"last_affected":[],"package":"github.com/vapor/leaf-kit","purl":"pkg:swift/github.com/vapor/leaf-kit","source":"GHSA-rv3x-xq3r-8j9h"}],"prev":{"headline":"XSS via d-popover and d-html-popover attribute","id":"CVE-2021-37633"},"products":["leaf-kit"],"published":"2021-08-09","related":[{"cvss_score":6.9,"headline":"LeafKit's HTML escaping may be skipped for Collection values, enabling XSS","id":"CVE-2026-28499","kev_date_added":null,"published":"2026-03-18"},{"cvss_score":6.1,"headline":"Leaf-kit html escaping does not work on characters that are part of extended grapheme cluster","id":"CVE-2026-27120","kev_date_added":null,"published":"2026-02-20"}],"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":null,"exploitation":null,"technical_impact":null},"state":"PUBLISHED","updated":"2024-08-04","vendors":["vapor"]},"summary":"Attackers can inject malicious scripts into web pages via unsanitized user input in LeafKit templates, potentially compromising user sessions.","url":"https://insights.sbomify.com/CVE-2021-37634/"}