Vulnerability · Published Oct 2, 2026 · Assigned by Bugcrowd

CVE-2026-104480Improper MLS Welcome roster validation in Discord libdave allows unauthorized group membership

Critical 9.4

In plain English

A critical-severity incorrect authorization in libdave from Discord. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 34% of all known vulnerabilities).

Severity (CVSS 4.0)9.4Critical

Exploit odds (30 days)0.4%top 65.9% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

Discord libdave before 1.2.0 did not reject an MLS Welcome message when the resulting group roster contained an unrecognized participant. An attacker in control of the DAVE signaling path (the voice gateway, or an equivalent position able to add, alter, or withhold signaling messages to a client) could cause affected clients to accept an unauthorized member into the end-to-end encrypted media session, compromising the confidentiality and integrity of audio and video.

Affected products (as reported)

Vendor	Product	Versions
Discord	libdave	1.1.0 – before 1.2.07b15f1fc16f159da0478aa6be909e38f1e957833 – before 9686fbaea864aa19f0675e486672b6a77811b6a1

Weakness: CWE-390, CWE-863 · Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N

References

[cpp] restore strict validation of MLS welcome state patch
libdave v1.2.0 release notes release-notes
Discord Audio and Video End-to-End Encryption (DAVE) Protocol Whitepaper technical-description
https://github.com/discord/libdave product