CVE-2026-55778 json
Parse Server: Stored XSS via non-standard file extension bypassing file upload extension blocklist
published 2026-06-19 4 mo ago modified 2026-10-25 14 d ago also BIT-parse-2026-55778 , EUVD-2026-42414 , GHSA-v8x7-r927-cc93
- cvss
- 2.1
- version 4.0, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.6%
- EPSS 0.6% chance of exploitation in 30 days, percentile 46%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- npm parse-server 8.6.81, 9.9.1-alpha.11
- bitnami parse 8.6.81, 9.9.1
- parseplatform parse-server 8.6.81, 9.9.1-alpha.11
- parseplatform parse_server 8.6.81, 9.9.1-alpha.11
- github.com/parse-community/parse-server@97c6a78 commit
- github.com/parse-community/parse-server@be12a60 commit
- github.com/parse-community/parse-server#10505 pull request
- github.com/parse-community/parse-server#10506 pull request
- github.com/parse-community/parse-server/releases/tag/8.6.81 release
- github.com/parse-community/parse-server/releases/tag/9.9.1-alpha.11 release
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
- Assessed
- 4 mo ago
Exploit prediction
0.55% chance of exploitation in the next 30 days, higher than 46% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 4.0 | 2.1 | 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 |
| CNA | 4.0 | 2.1 | 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| npm | parse-server | >=9.0.0, <9.9.1-alpha.11 <8.6.81 |
9.9.1-alpha.11 8.6.81 |
| bitnami | parse | <8.6.81 >=9.0.0, <9.9.1 |
8.6.81 9.9.1 |
Affected products
- parse-community parse-server
Classification
- Weakness
-
- CWE-434 Unrestricted Upload of File with Dangerous Type
References
-
github.com
/parse-community/parse-server/pull/10505
web
-
github.com
/parse-community/parse-server/pull/10506
web
-
github.com
/parse-community/parse-server/commit/97c6a78d19f976ec756c1295f08a8fccab90799a
web
-
github.com
/parse-community/parse-server/commit/be12a60d65b6e140481882037fb896b1f951df50
web
-
github.com
/parse-community/parse-server/security/advisories/GHSA-v8x7-r927-cc93
web
-
github.com
/parse-community/parse-server/releases/tag/8.6.81
web
-
github.com
/parse-community/parse-server/releases/tag/9.9.1-alpha.11
web
-
github.com
/parse-community/parse-server
package
-
nvd.nist.gov
/vuln/detail/CVE-2026-55778
web
Sources
- CVE List CVE-2026-55778
- GitHub Advisory GHSA-v8x7-r927-cc93
- NVD CVE-2026-55778
- OSV BIT-parse-2026-55778
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.
CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.