{"id":"CVE-2026-55778","state":"PUBLISHED","title":"Parse Server: Stored XSS via non-standard file extension bypassing file upload extension blocklist","description":"Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to 9.9.1-alpha.11 and 8.6.81, the default fileUpload.fileExtensions blocklist could be bypassed by uploading a file with a non-standard or compound extension and dangerous content type, allowing storage adapters such as S3 and GCS to serve attacker-supplied active content and enable stored cross-site scripting. This issue is fixed in versions 9.9.1-alpha.11 and 8.6.81.","publishedAt":"2026-07-08T20:50:52.531Z","updatedAt":"2026-07-09T13:39:44.881Z","severity":{"score":2.1,"label":"Low","version":"4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["parse-community parse-server"],"affected":[{"vendor":"parse-community","product":"parse-server","versions":[{"version":">= 9.0.0-alpha.1, < 9.9.1-alpha.11","status":"affected"},{"version":"< 8.6.81","status":"affected"}]}],"references":["https://github.com/parse-community/parse-server/security/advisories/GHSA-v8x7-r927-cc93","https://github.com/parse-community/parse-server/pull/10505","https://github.com/parse-community/parse-server/pull/10506","https://github.com/parse-community/parse-server/commit/97c6a78d19f976ec756c1295f08a8fccab90799a","https://github.com/parse-community/parse-server/commit/be12a60d65b6e140481882037fb896b1f951df50","https://github.com/parse-community/parse-server/releases/tag/8.6.81","https://github.com/parse-community/parse-server/releases/tag/9.9.1-alpha.11"],"weaknesses":["CWE-434"],"ingestedAt":"2026-10-29T20:12:24.861Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/55xxx/CVE-2026-55778.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-55778","state":"PUBLISHED","datePublished":"2026-07-08T20:50:52.531Z","dateUpdated":"2026-07-09T13:39:44.881Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-06-17T14:40:28.379Z"},"containers":{"cna":{"title":"Parse Server: Stored XSS via non-standard file extension bypassing file upload extension blocklist","descriptions":[{"lang":"en","value":"Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to 9.9.1-alpha.11 and 8.6.81, the default fileUpload.fileExtensions blocklist could be bypassed by uploading a file with a non-standard or compound extension and dangerous content type, allowing storage adapters such as S3 and GCS to serve attacker-supplied active content and enable stored cross-site scripting. This issue is fixed in versions 9.9.1-alpha.11 and 8.6.81."}],"affected":[{"vendor":"parse-community","product":"parse-server","versions":[{"version":">= 9.0.0-alpha.1, < 9.9.1-alpha.11","status":"affected"},{"version":"< 8.6.81","status":"affected"}]}],"references":[{"url":"https://github.com/parse-community/parse-server/security/advisories/GHSA-v8x7-r927-cc93","name":"https://github.com/parse-community/parse-server/security/advisories/GHSA-v8x7-r927-cc93","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/parse-community/parse-server/pull/10505","name":"https://github.com/parse-community/parse-server/pull/10505","tags":["x_refsource_MISC"]},{"url":"https://github.com/parse-community/parse-server/pull/10506","name":"https://github.com/parse-community/parse-server/pull/10506","tags":["x_refsource_MISC"]},{"url":"https://github.com/parse-community/parse-server/commit/97c6a78d19f976ec756c1295f08a8fccab90799a","name":"https://github.com/parse-community/parse-server/commit/97c6a78d19f976ec756c1295f08a8fccab90799a","tags":["x_refsource_MISC"]},{"url":"https://github.com/parse-community/parse-server/commit/be12a60d65b6e140481882037fb896b1f951df50","name":"https://github.com/parse-community/parse-server/commit/be12a60d65b6e140481882037fb896b1f951df50","tags":["x_refsource_MISC"]},{"url":"https://github.com/parse-community/parse-server/releases/tag/8.6.81","name":"https://github.com/parse-community/parse-server/releases/tag/8.6.81","tags":["x_refsource_MISC"]},{"url":"https://github.com/parse-community/parse-server/releases/tag/9.9.1-alpha.11","name":"https://github.com/parse-community/parse-server/releases/tag/9.9.1-alpha.11","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"PRESENT","privilegesRequired":"LOW","userInteraction":"PASSIVE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"LOW","vulnAvailabilityImpact":"NONE","subConfidentialityImpact":"LOW","subIntegrityImpact":"LOW","subAvailabilityImpact":"NONE","baseScore":2.1,"baseSeverity":"LOW","vectorString":"CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N","version":"4.0"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-434","lang":"en","description":"CWE-434: Unrestricted Upload of File with Dangerous Type","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-07-08T20:50:52.531Z"},"source":{"advisory":"GHSA-v8x7-r927-cc93","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-07-09T13:39:32.908358Z","id":"CVE-2026-55778","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-07-09T13:39:44.881Z"}}]}}}