{"id":"CVE-2026-33994","state":"PUBLISHED","title":"Locutus Prototype Pollution due to incomplete fix for CVE-2026-25521","description":"Locutus brings stdlibs of other programming languages to JavaScript for educational purposes. Starting in version 2.0.39 and prior to version 3.0.25, a prototype pollution vulnerability exists in the `parse_str` function of the npm package locutus. An attacker can pollute `Object.prototype` by overriding `RegExp.prototype.test` and then passing a crafted query string to `parse_str`, bypassing the prototype pollution guard. This vulnerability stems from an incomplete fix for CVE-2026-25521. The CVE-2026-25521 patch replaced the `String.prototype.includes()`-based guard with a `RegExp.prototype.test()`-based guard. However, `RegExp.prototype.test` is itself a writable prototype method that can be overridden, making the new guard bypassable in the same way as the original — trading one hijackable built-in for another. Version 3.0.25 contains an updated fix.","publishedAt":"2026-03-27T22:15:47.131Z","updatedAt":"2026-04-01T13:45:55.451Z","severity":{"score":6.3,"label":"Medium","version":"4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["locutusjs locutus"],"affected":[{"vendor":"locutusjs","product":"locutus","versions":[{"version":">= 2.0.39, < 3.0.25","status":"affected"}]}],"references":["https://github.com/locutusjs/locutus/security/advisories/GHSA-vc8f-x9pp-wf5p","https://github.com/locutusjs/locutus/pull/597","https://github.com/locutusjs/locutus/commit/345a6211e1e6f939f96a7090bfeff642c9fcf9e4","https://github.com/locutusjs/locutus/releases/tag/v3.0.25"],"weaknesses":["CWE-1321"],"ingestedAt":"2026-10-29T20:11:40.391Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/33xxx/CVE-2026-33994.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-33994","state":"PUBLISHED","datePublished":"2026-03-27T22:15:47.131Z","dateUpdated":"2026-04-01T13:45:55.451Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-03-24T22:20:06.212Z"},"containers":{"cna":{"title":"Locutus Prototype Pollution due to incomplete fix for CVE-2026-25521","descriptions":[{"lang":"en","value":"Locutus brings stdlibs of other programming languages to JavaScript for educational purposes. Starting in version 2.0.39 and prior to version 3.0.25, a prototype pollution vulnerability exists in the `parse_str` function of the npm package locutus. An attacker can pollute `Object.prototype` by overriding `RegExp.prototype.test` and then passing a crafted query string to `parse_str`, bypassing the prototype pollution guard. This vulnerability stems from an incomplete fix for CVE-2026-25521. The CVE-2026-25521 patch replaced the `String.prototype.includes()`-based guard with a `RegExp.prototype.test()`-based guard. However, `RegExp.prototype.test` is itself a writable prototype method that can be overridden, making the new guard bypassable in the same way as the original — trading one hijackable built-in for another. Version 3.0.25 contains an updated fix."}],"affected":[{"vendor":"locutusjs","product":"locutus","versions":[{"version":">= 2.0.39, < 3.0.25","status":"affected"}]}],"references":[{"url":"https://github.com/locutusjs/locutus/security/advisories/GHSA-vc8f-x9pp-wf5p","name":"https://github.com/locutusjs/locutus/security/advisories/GHSA-vc8f-x9pp-wf5p","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/locutusjs/locutus/security/advisories/GHSA-vc8f-x9pp-wf5p","name":"https://github.com/locutusjs/locutus/security/advisories/GHSA-vc8f-x9pp-wf5p","tags":["x_refsource_MISC"]},{"url":"https://github.com/locutusjs/locutus/pull/597","name":"https://github.com/locutusjs/locutus/pull/597","tags":["x_refsource_MISC"]},{"url":"https://github.com/locutusjs/locutus/commit/345a6211e1e6f939f96a7090bfeff642c9fcf9e4","name":"https://github.com/locutusjs/locutus/commit/345a6211e1e6f939f96a7090bfeff642c9fcf9e4","tags":["x_refsource_MISC"]},{"url":"https://github.com/locutusjs/locutus/releases/tag/v3.0.25","name":"https://github.com/locutusjs/locutus/releases/tag/v3.0.25","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"PRESENT","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"LOW","vulnAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"LOW","subAvailabilityImpact":"NONE","baseScore":6.3,"baseSeverity":"MEDIUM","vectorString":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N","version":"4.0"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-1321","lang":"en","description":"CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-03-27T22:15:47.131Z"},"source":{"advisory":"GHSA-vc8f-x9pp-wf5p","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"cvssV3_1":{"scope":"UNCHANGED","version":"3.1","baseScore":9.8,"attackVector":"NETWORK","baseSeverity":"CRITICAL","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","integrityImpact":"HIGH","userInteraction":"NONE","attackComplexity":"LOW","availabilityImpact":"HIGH","privilegesRequired":"NONE","confidentialityImpact":"HIGH"}},{"other":{"type":"ssvc","content":{"timestamp":"2026-04-01T13:45:33.039333Z","id":"CVE-2026-33994","options":[{"Exploitation":"poc"},{"Automatable":"yes"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-04-01T13:45:55.451Z"}}]}}}