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GHSA-6r2j-cxgf-495f

CriticalCVSS 9.9 / 10

Published Mar 11, 2026·Last modified Mar 14, 2026

Affected Components(0)

No affected components available

Description

Impact

A vulnerability in Parse Server's query handling allows an authenticated or unauthenticated attacker to exfiltrate session tokens of other users by exploiting the redirectClassNameForKey query parameter. Exfiltrated session tokens can be used to take over user accounts.

The vulnerability requires the attacker to be able to create or update an object with a new relation field, which depends on the Class-Level Permissions of at least one class.

Patches

The fix applies the same security checks that normally protect class access after the query redirect, ensuring that queries redirected via redirectClassNameForKey are subject to the same restrictions as direct queries to the target class.

Workarounds

Set restrictive Class-Level Permissions to prevent clients from creating new fields on classes, specifically by disabling addField for public access and unauthenticated users. Note that this limits client functionality and does not fully eliminate the risk if a relation field pointing to a protected class already exists in the schema.

References

GitHub security advisory: https://github.com/parse-community/parse-server/security/advisories/GHSA-6r2j-cxgf-495f
Fix Parse Server 9: https://github.com/parse-community/parse-server/releases/tag/9.5.2-alpha.8
Fix Parse Server 8: https://github.com/parse-community/parse-server/releases/tag/8.6.21

Risk Scores

Base Score

9.9

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability.

Threat Intelligence

8.9

Exploitation activity has been observed. Apply available patches or mitigations urgently.

EPSS

0.36%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit

Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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Critical severity

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