How severe is CVE-2026-27804?

CVE-2026-27804 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.

Is CVE-2026-27804 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (7th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-27804?

CVE-2026-27804 primarily affects Parseplatform Parse-server. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-27804?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

Does CVE-2026-27804 have an EU (EUVD) identifier?

Yes. CVE-2026-27804 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-8774.

When was CVE-2026-27804 published?

CVE-2026-27804 was published on 2026-02-26 and last updated on 2026-06-17.

CVE-2026-27804

CVE-2026-27804 is a critical-severity vulnerability in Parseplatform Parse-server with a CVSS 3.x base score of 9.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-327.

Key facts

Severity: Critical (CVSS 3.x base score 9.1)
CVSS v4: 9.3
EPSS exploit prediction: 0% (7th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-8774
Weakness: CWE-327
Affected product: Parseplatform Parse-server
Published: 2026-02-26
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2026-27804?: 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.
How severe is CVE-2026-27804?: CVE-2026-27804 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.
Is CVE-2026-27804 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (7th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-27804?: CVE-2026-27804 primarily affects Parseplatform Parse-server. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-27804?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2026-27804 have an EU (EUVD) identifier?: Yes. CVE-2026-27804 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-8774.
When was CVE-2026-27804 published?: CVE-2026-27804 was published on 2026-02-26 and last updated on 2026-06-17.

References

Affected products (4)

cpe:2.3:a:parseplatform:parse-server:*:*:*:*:*:node.js:*:*
cpe:2.3:a:parseplatform:parse-server:9.3.1:alpha1:*:*:*:node.js:*:*
cpe:2.3:a:parseplatform:parse-server:9.3.1:alpha2:*:*:*:node.js:*:*
cpe:2.3:a:parseplatform:parse-server:9.3.1:alpha3:*:*:*:node.js:*:*

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