CVE-2026-40300
Zulip: Message edit history visible in "moves only" policy through /api/v1/messages/{id}/history
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Prior to 12.0, With message_edit_history_visibility_policy set to "moves", /api/v1/messages/{id}/history still returns historical content values, allowing low-privilege users to recover text that was edited away from other users' messages.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.
INFO
Published Date :
May 12, 2026, 5:16 p.m.
Last Modified :
May 13, 2026, 6:58 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | MEDIUM | [email protected] | ||||
| CVSS 4.0 | MEDIUM | [email protected] |
Solution
- Update Zulip to version 12.0 or later.
- Verify message history visibility policy configuration.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-40300.
| URL | Resource |
|---|---|
| https://github.com/zulip/zulip/security/advisories/GHSA-jp8f-mvv6-89cr | Exploit Vendor Advisory |
| https://github.com/zulip/zulip/security/advisories/GHSA-jp8f-mvv6-89cr | Exploit Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-40300 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-40300
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-40300 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-40300 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
May. 13, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N Added CWE NVD-CWE-noinfo Added CPE Configuration OR *cpe:2.3:a:zulip:zulip_server:10.0:*:*:*:*:*:*:* Added Reference Type CISA-ADP: https://github.com/zulip/zulip/security/advisories/GHSA-jp8f-mvv6-89cr Types: Exploit, Vendor Advisory Added Reference Type GitHub, Inc.: https://github.com/zulip/zulip/security/advisories/GHSA-jp8f-mvv6-89cr Types: Exploit, Vendor Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
May. 13, 2026
Action Type Old Value New Value Added Reference https://github.com/zulip/zulip/security/advisories/GHSA-jp8f-mvv6-89cr -
New CVE Received by [email protected]
May. 12, 2026
Action Type Old Value New Value Added 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. Added CVSS V4.0 AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/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 Added CWE CWE-284 Added Reference https://github.com/zulip/zulip/security/advisories/GHSA-jp8f-mvv6-89cr