What’s Vulnerable › Vulnerabilities

CVE-2021-37843

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-08-02 · updated 2026-06-17
• Weakness: CWE-306

Description

The resolution SAML SSO apps for Atlassian products allow a remote attacker to login to a user account when only the username is known (i.e., no other authentication is provided). The fixed versions are for Jira: 3.6.6.1, 4.0.12, 5.0.5; for Confluence 3.6.6, 4.0.12, 5.0.5; for Bitbucket 2.5.9, 3.6.6, 4.0.12, 5.0.5; for Bamboo 2.5.9, 3.6.6, 4.0.12, 5.0.5; and for Fisheye 2.5.9.

Affected products

• Atlassian Saml Single Sign On: before 2.5.9; before 3.5.6; before 3.6.6.1; from 3.0.0 before 3.6.6; from 3.6.0 before 3.6.6.1; from 4.0.0 before 4.0.12 — fixed in 2.5.9, 3.5.6, 3.6.6, 3.6.6.1, 4.0.12, 5.0.5

How to fix

Upgrade to a fixed version: Atlassian Saml Single Sign On 2.5.9, 3.5.6, 3.6.6, 3.6.6.1. Check the vendor advisory for mitigations.

References

• https://wiki.resolution.de/doc/saml-sso/5.0.x/all/security-advisories/2021-07-29-authentication-bypass-network-attacker-can-login-to-users-accounts-when-usernames-are-known
• https://wiki.resolution.de/doc/saml-sso/5.0.x/all/security-advisories/2021-07-29-authentication-bypass-network-attacker-can-login-to-users-accounts-when-usernames-are-known

Get alerted when CVE-2021-37843 or the next vulnerability affects your stack