CVE-2026-40300 — MEDIUM (6.5)

Vulnerability Description

Zulip is an open-source team collaboration tool. Prior to 12.0, With message_edit_history_visibility_policy set to "moves", /api/v1/messages/{id}/history still returns historical content values, allowing low-privilege users to recover text that was edited away from other users' messages. This vulnerability is fixed in 12.0.

CVSS Score

6.5

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

LOW

User Interaction

NONE

Scope

UNCHANGED

Confidentiality

HIGH

Integrity

NONE

Availability

NONE

Affected Products

Vendor	Product	Versions
Zulip	Zulip Server	10.0

Related Weaknesses (CWE)

CWE-284

References

https://github.com/zulip/zulip/security/advisories/GHSA-jp8f-mvv6-89crExploitVendor Advisory
https://github.com/zulip/zulip/security/advisories/GHSA-jp8f-mvv6-89crExploitVendor Advisory

FAQ

What is CVE-2026-40300?

CVE-2026-40300 is a vulnerability with a CVSS score of 6.5 (MEDIUM). Zulip is an open-source team collaboration tool. Prior to 12.0, With message_edit_history_visibility_policy set to "moves", /api/v1/messages/{id}/history still returns historical content values, allow...

How severe is CVE-2026-40300?

CVE-2026-40300 has been rated MEDIUM with a CVSS base score of 6.5/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-40300?

Check the references section above for vendor advisories and patch information. Affected products include: Zulip Zulip Server.