{"answers":{"affected":"2 open source packages ship an affected version, including handlebars. It affects 1 product.","exploited":"It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-33939 exists.","fix":"Upgrade handlebars to 4.7.9 or later.","what":"CVE-2026-33939 is a high-severity denial of service vulnerability in handlebars-lang handlebars.js, published on 27 Mar 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-2026-33939 and fix it if it is affected.\n\nWhat it is: CVE-2026-33939 is a high-severity denial of service vulnerability in handlebars-lang handlebars.js, published on 27 Mar 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-2026-33939 exists.\n\nAffected packages and fixed versions:\n- handlebars (npm): affected from 4.0.0; fixed in 4.7.9\n- handlebars (npm): affected from 4.0.0; fixed in 4.7.9\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-2026-33939/ (Markdown: https://insights.sbomify.com/CVE-2026-33939/index.md)","id":"CVE-2026-33939","markdown":"https://insights.sbomify.com/CVE-2026-33939/index.md","name":"CVE-2026-33939","record":{"aliases":["CLEANSTART-2026-JZ33423","CLEANSTART-2026-YO10703","DEBIAN-CVE-2026-33939","GHSA-9cx6-37pm-9jff","MINI-4gh3-6qch-78xm","MINI-5gv5-223m-qmx4","MINI-626h-fcp8-gx78","MINI-8mqq-23v7-qq8m","MINI-9wmc-hx6q-73g7","MINI-f5fg-97q3-hmf7","MINI-hc2j-j87m-9f4h","MINI-hq9r-8wj2-8whr","MINI-pqxg-v2w6-xhr7","MINI-r26x-4v53-cw6g","MINI-rc4v-pjj8-hc9c","MINI-vg9x-cg67-hhq5","MINI-wxcq-fcr6-chqx","MINI-x97r-7ffq-vqfh","ROOT-APP-NPM-CVE-2026-33939","UBUNTU-CVE-2026-33939"],"analysis":{"component_type":"library","fix_type":"upgrade","impacts":["denial_of_service"],"network_reachable":"yes","non_default_config":false,"product_category":"JavaScript templating library","requires_auth":"none","summary":"Attackers can crash Node.js applications by supplying templates with malformed decorator syntax, causing an unhandled TypeError during compilation.","user_interaction":"not_required","vuln_class":"denial_of_service"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"GitHub_M","cpe":[{"product":"handlebars","vendor":"handlebarsjs"}],"cvss":{"score":7.5,"severity":"high","source":"cna","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","version":"3.1"},"cwes":[{"id":"CWE-248","name":"Uncaught Exception"},{"id":"CWE-754","name":"Improper Check for Unusual or Exceptional Conditions"}],"description":"Handlebars provides the power necessary to let users build semantic templates. In versions 4.0.0 through 4.7.8, when a Handlebars template contains decorator syntax referencing an unregistered decorator (e.g. `{{*n}}`), the compiled template calls `lookupProperty(decorators, \"n\")`, which returns `undefined`. The runtime then immediately invokes the result as a function, causing an unhandled `TypeError: ... is not a function` that crashes the Node.js process. Any application that compiles user-supplied templates without wrapping the call in a `try/catch` is vulnerable to a single-request Denial of Service. Version 4.7.9 fixes the issue. Some workarounds are available. Wrap compilation and rendering in `try/catch`. Validate template input before passing it to `compile()`; reject templates containing  decorator syntax (`{{*...}}`) if decorators are not used in your application. Use the pre-compilation workflow; compile templates at build time and serve only pre-compiled  templates; do not call `compile()` at request time.","ecosystems":["npm"],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"weaponised"},"has_fix":true,"headline":"Handlebars.js has Denial of Service via Malformed Decorator Syntax in Template Compilation","id":"CVE-2026-33939","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":"npm","product":null,"products":[],"type":"denial_of_service","year":"2026"},"n_packages":2,"n_references":3,"next":{"headline":"Handlebars.js has JavaScript Injection via AST Type Confusion when passing an object as dynamic partial","id":"CVE-2026-33940"},"packages":[{"ecosystem":"npm","fixed":["4.7.9"],"introduced":["4.0.0"],"last_affected":[],"package":"handlebars","purl":null,"source":"GHSA-9cx6-37pm-9jff"},{"ecosystem":"npm","fixed":["4.7.9"],"introduced":["4.0.0"],"last_affected":[],"package":"handlebars","purl":"pkg:npm/handlebars","source":"GHSA-9cx6-37pm-9jff"}],"prev":{"headline":"Handlebars.js has JavaScript Injection via AST Type Confusion by tampering @partial-block","id":"CVE-2026-33938"},"products":["handlebars.js"],"published":"2026-03-27","related":[{"cvss_score":9.8,"headline":"Handlebars.js has JavaScript Injection via AST Type Confusion","id":"CVE-2026-33937","kev_date_added":null,"published":"2026-03-27"},{"cvss_score":8.3,"headline":"Handlebars.js has JavaScript Injection in CLI Precompiler via Unescaped Names and Options","id":"CVE-2026-33941","kev_date_added":null,"published":"2026-03-27"},{"cvss_score":8.1,"headline":"Handlebars.js has JavaScript Injection via AST Type Confusion by tampering @partial-block","id":"CVE-2026-33938","kev_date_added":null,"published":"2026-03-27"},{"cvss_score":8.1,"headline":"Handlebars.js has JavaScript Injection via AST Type Confusion when passing an object as dynamic partial","id":"CVE-2026-33940","kev_date_added":null,"published":"2026-03-27"},{"cvss_score":8.1,"headline":"Arbitrary Code Execution in Handlebars","id":"CVE-2019-20920","kev_date_added":null,"published":"2020-09-30"},{"cvss_score":7.5,"headline":"Regular Expression Denial of Service in Handlebars","id":"CVE-2019-20922","kev_date_added":null,"published":"2020-09-30"}],"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":"yes","exploitation":"poc","technical_impact":"partial"},"state":"PUBLISHED","updated":"2026-09-04","vendors":["handlebars-lang"]},"summary":"Attackers can crash Node.js applications by supplying templates with malformed decorator syntax, causing an unhandled TypeError during compilation.","url":"https://insights.sbomify.com/CVE-2026-33939/"}