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Fencer Intel
critical 9.1

CVE-2026-27804 json

Parse Server: Account takeover via JWT algorithm confusion in Google auth adapter

published 8mo ago modified 2mo ago also BIT-parse-2026-27804 , EUVD-2026-8774 , GHSA-4q3h-vp4r-prv2

cvss
9.1
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 10%
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 8.6.3 and 9.1.1-alpha.4, an unauthenticated attacker can forge a Google authentication token with `alg: "none"` to log in as any user linked to a Google account, without knowing their credentials. All deployments with Google authentication enabled are affected. The fix in versions 8.6.3 and 9.1.1-alpha.4 hardcodes the expected `RS256` algorithm instead of trusting the JWT header, and replaces the Google adapter's custom key fetcher with `jwks-rsa` which rejects unknown key IDs. As a workaround, dsable Google authentication until upgrading is possible.

Patch / fix

  • npm parse-server 8.6.3, 9.3.1-alpha.4
  • bitnami parse 8.6.3, 9.3.1
  • parseplatform parse-server 8.6.3, 9.3.1-alpha.4
  • parseplatform parse_server 8.6.3, 9.3.1-alpha.4

Is CVE-2026-27804 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
total
Assessed
8mo ago

Exploit prediction

0.20% chance of exploitation in the next 30 days, higher than 10% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 4.0 9.3 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
CNA 4.0 9.3 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/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
NVD 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Affected packages

ecosystem package affected fixed in
npm parse-server
>=9.0.0, <9.3.1-alpha.4
<8.6.3
9.3.1-alpha.4
8.6.3
bitnami parse
<8.6.3
>=9.0.0, <9.3.1
8.6.3
9.3.1

Affected products

  • parse-community parse-server

Classification

Weakness
  • CWE-327 Use of a Broken or Risky Cryptographic Algorithm
  • CWE-345 Insufficient Verification of Data Authenticity

References

Sources

Fencer Intel 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.