Misskey is an open source, federated social media platform. Prior to 2026.6.0, Misskey contains a vulnerability in Time-based One-Time Password (TOTP) authentication in UserAuthService where insufficient validation of used tokens allows the reuse of a single-use code within its valid time step. If both credentials and a TOTP code are obtained concurrently, an attacker may reuse the code to perform unauthorized actions, potentially leading to account takeover. This issue is fixed in version 2026.6.0.
https://github.com/misskey-dev/misskey/security/advisories/GHSA-2m5x-5mp6-6vpq
https://github.com/misskey-dev/misskey/releases/tag/2026.6.0
https://github.com/misskey-dev/misskey/commit/d323fe00d04ac46ab0b4e66fce9169effaa8dfb7
https://github.com/misskey-dev/misskey/commit/00c6210a591db2b0be438740d05b82070fa68ac6
Published: 2026-07-10
Updated: 2026-07-10
Base Score: 7.5
Vector: CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:P
Severity: High
Base Score: 9.8
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Severity: Critical
Base Score: 7.4
Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
Severity: High
EPSS: 0.0034