CVE-2026-21588

State: Published
Severity: 7.1 High
Published: Sep 15, 2026
Updated: Sep 15, 2026
Reserved: Jan 1, 2026

Description

This High severity DoS (Denial of Service) vulnerability was introduced in versions 8.9.0, 9.0.1, 9.1.0, 9.2.0, 9.3.1, 9.4.0, 9.5.1, 10.0.2, 10.1.0, and 10.2.0 of Confluence Data Center.

This DoS (Denial of Service) vulnerability, with a CVSS Score of 7.1, allows an authenticated attacker to cause a resource to be unavailable for its intended users by temporarily or indefinitely disrupting services of a host connected to a network.

Atlassian recommends that Confluence Data Center customers upgrade to latest version, if you are unable to do so, upgrade your instance to one of the specified supported fixed versions: Confluence Data Center 9.2: Upgrade to a release greater than or equal to 9.2.24

Confluence Data Center 10.2: Upgrade to a release greater than or equal to 10.2.17

See the release notes ([https://confluence.atlassian.com/doc/confluence-release-notes-327.html]). You can download the latest version of Confluence Data Center from the download center ([https://www.atlassian.com/software/confluence/download-archives]).

This vulnerability was reported via our Penetration Testing program.

Scores

CVSS	Score	Vector	Source
4.0	7.1 High	CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N	atlassian

Weaknesses

CWE-400 Uncontrolled Resource Consumption

Affected Products

Product	Versions
Confluence Data CenterAtlassian	10.2.0 to 10.2.15Affected 10.1.0 to 10.1.2Affected 10.0.2 to 10.0.3Affected 9.5.1 to 9.5.4Affected 9.4.0 to 9.4.1Affected 9.3.1 to 9.3.2Affected 9.2.0 to 9.2.23Affected 9.1.0 to 9.1.1Affected 8.9.7 to 8.9.8Affected 10.2.17 to 10.2.18Not affected 9.2.24 to 9.2.25Not affected

References

Every record here comes from the CVE Program’s CVE List. © 1999–2026 The MITRE Corporation. CVE is a registered trademark of The MITRE Corporation. The records are reproduced under the CVE Program terms of use.