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TI-2026-40267 Aliases CVE-2026-55778GHSA-v8x7-r927-cc93

Parse Server: Stored XSS via non-standard file extension bypassing file upload extension blocklist

Priority LOW 12CWE-434Published · Updated

Key facts

Attack vector
Network
Privileges required
Low
User interaction
Passive
Attack complexity
Low
Attack requirements
Present
Impact type
Code execution
Confidentiality · integrity · availability
None · Low · None
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA and GitHub. Impact type from CWE-434.

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00553 46th percentileScored 2026-11-07
Fix Fixed parse-server (parse-community): 9.9.1-alpha.11, 8.6.81parse-server (npm): 9.9.1-alpha.11, 8.6.81

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
parse-communityparse-server9.0.0-alpha.1 to before 9.9.1-alpha.11; before 8.6.819.9.1-alpha.11, 8.6.81Patch availableCNA
—parse-server (npm)9.0.0 to before 9.9.1-alpha.119.9.1-alpha.11Patch availableGHSA-v8x7-r927-cc93
—parse-server (npm)before 8.6.818.6.81Patch availableGHSA-v8x7-r927-cc93
  • parse-server Vendorparse-community Affected 9.0.0-alpha.1 to before 9.9.1-alpha.11; before 8.6.81 Fixed in 9.9.1-alpha.11, 8.6.81 Patch available CNA
  • parse-server (npm) Vendor— Affected 9.0.0 to before 9.9.1-alpha.11 Fixed in 9.9.1-alpha.11 Patch available GHSA-v8x7-r927-cc93
  • parse-server (npm) Vendor— Affected before 8.6.81 Fixed in 8.6.81 Patch available GHSA-v8x7-r927-cc93

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPEVersionsRoleVendor
cpe:2.3:a:parseplatform:parse-server:*:*:*:*:*:*:*:*——parse-community
  • cpe:2.3:a:parseplatform:parse-server:*:*:*:*:*:*:*:* Versions — — ·parse-community

Remediation

  • Fix · CNA parse-server (parse-community) Fixed in 9.9.1-alpha.11, 8.6.81
  • Fix · GHSA-v8x7-r927-cc93 parse-server (npm) Fixed in 9.9.1-alpha.11 Advisory →
  • Fix · GHSA-v8x7-r927-cc93 parse-server (npm) Fixed in 8.6.81 Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-55778
  2. 2026-10-03 Alias added: GHSA-v8x7-r927-cc93

References

Other 8

  • TI-2022-08574 Command Injection in Parse server CVSS 3.1CRITICAL 10.0
  • TI-2024-18136 Parse Server literalizeRegexPart SQL Injection CVSS 3.1CRITICAL 10.0
  • TI-2022-18768 Parse Server vulnerable to Remote Code Execution via prototype pollution in MongoDB BSON parser CVSS 3.1CRITICAL 9.8
  • TI-2024-31550 Parse Server's custom object ID allows to acquire role privileges CVSS 3.1HIGH 8.1
  • TI-2025-35510 parse is a package designed to parse JavaScript SDK. CVSS 3.1MEDIUM 6.5
  • TI-2024-26265 ZDI-CAN-23894: Parse Server literalizeRegexPart SQL Injection Authentication Bypass Vulnerability CVSS 3.1CRITICAL 9.8
See all 158 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences