Authentication Bypass by Assumed-Immutable Data Affecting github.com/zitadel/zitadel/internal/authz/repository/eventsourcing/eventstore package, versions <1.80.0-v2.20.0.20260216092519-feab8e1fa371>=2.31.0 <3.4.7>=4.0.0-rc.1 <4.11.0
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-GOLANG-GITHUBCOMZITADELZITADELINTERNALAUTHZREPOSITORYEVENTSOURCINGEVENTSTORE-15369731
- published3 Mar 2026
- disclosed27 Feb 2026
- creditOlivier Becker, Lucas Dodgson
Introduced: 27 Feb 2026
CVE-2026-27840 Â (opens in a new tab)How to fix?
Upgrade github.com/zitadel/zitadel/internal/authz/repository/eventsourcing/eventstore to version 1.80.0-v2.20.0.20260216092519-feab8e1fa371, 3.4.7, 4.11.0 or higher.
Overview
Affected versions of this package are vulnerable to Authentication Bypass by Assumed-Immutable Data in the verifyAccessTokenV2() function that accepts truncated tokens as the valid ones. An attacker can cause the system to accept truncated tokens missing the user_id by submitting an opaque OIDC access token with the cleartext payload shortened to 80 characters.