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Fencer Vulns
low 2.1

CVE-2026-53724 json

Parse Server: Stored XSS via trailing-dot filename bypassing file upload extension blocklist

published 2026-06-12 4 mo ago modified 2026-10-26 14 d ago also BIT-parse-2026-53724 , EUVD-2026-36539 , GHSA-7wqv-xjf3-x35v

cvss
2.1
version 4.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 20%
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 versions 8.6.79 and 9.9.1-alpha.4, the default file upload extension blocklist can be bypassed by appending a trailing dot to a filename whose extension would otherwise be blocked (e.g. poc.svg.). The trailing dot causes the extension parser to extract an empty string, which short-circuits the blocklist check, and the attacker-controlled Content-Type is forwarded to the storage adapter unchanged. Storage adapters that persist and serve the provided Content-Type (such as S3 or GCS) then serve the file with an active type such as image/svg+xml, enabling stored XSS when a victim opens the file URL. The default GridFS adapter is not affected because it sets X-Content-Type-Options: nosniff on responses. This issue has been patched in versions 8.6.79 and 9.9.1-alpha.4.

Patch / fix

  • npm parse-server 8.6.79, 9.9.1-alpha.4
  • bitnami parse 8.6.79, 9.9.1
  • parseplatform parse-server 8.6.79, 9.9.1-alpha.4
  • parseplatform parse_server 8.6.79, 9.9.1-alpha.4

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
4 mo ago

Exploit prediction

0.28% chance of exploitation in the next 30 days, higher than 20% 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.4
<8.6.79
9.9.1-alpha.4
8.6.79
bitnami parse
<8.6.79
>=9.0.0, <9.9.1
8.6.79
9.9.1

Affected products

  • parse-community parse-server

Classification

Weakness
  • CWE-434 Unrestricted Upload of File with Dangerous Type
  • CWE-79 Improper Neutralization of Input During Web Page Generation

References

Sources

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.