parse-server's endpoint `/loginAs` allows `readOnlyMasterKey` to gain full read and write access as any user

Description

The readOnlyMasterKey can call POST /loginAs to obtain a valid session token for any user. This allows a read-only credential to impersonate arbitrary users with full read and write access to their data. Any Parse Server deployment that uses readOnlyMasterKey is affected.

Recommendation

Update the parse-server package to the latest compatible version. Followings are version details:

• Affected version(s): **>= 9.0.0, < 9.5.0-alpha.4

  < 8.6.6**

• Patched version(s): **9.5.0-alpha.4

  8.6.6**

References

• GHSA-79wj-8rqv-jvp5
• CVE-2026-30229
• CWE-863
• CAPEC-310
• OWASP 2021-A1
• OWASP 2021-A6

Related Issues

• Parse Server's Session Update endpoint allows overwriting server-generated session fields - CVE-2026-33527
• Parse Server session creation endpoint allows overwriting server-generated session fields - CVE-2026-32742
• Parse Server vulnerable to user enumeration via email verification endpoint - CVE-2026-31901
• Parse Server's Cloud Hooks and Cloud Jobs bypass `readOnlyMasterKey` write restriction - CVE-2026-29182

Tags:

npm

parse-server