Is CVE-2026-21577 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-21577 being exploited in the wild.

How severe is CVE-2026-21577?

Informational severity, with a CVSS score of 7.1, published 21 July 2026.

Which products and versions are affected?

Atlassian Confluence Data Center 9.0.1 to 9.5.4, 10.0.2 to 10.2.6.

Is there a fix for CVE-2026-21577?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-21577 attacked?

It is attacked over the network, in a network appliance.

Am I affected by CVE-2026-21577?

Check whether you run Atlassian Confluence Data Center at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-21577: Atlassian Confluence Data Center denial of service

CVE-2026-21577 · Severity: info · CVSS 7.1 · Published 2026-07-21

Atlassian Confluence Data Center, a popular team collaboration and documentation platform, is affected by a security flaw that could allow a user to crash the service. An authenticated attacker can exploit this vulnerability to make the platform unavailable to other employees, disrupting business operations and internal communications. Atlassian has released updates to resolve this issue and recommends upgrading to the latest version.

Technologies: Atlassian Confluence Data Center. Vendors: Atlassian.

Quick answers

Is CVE-2026-21577 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-21577 being exploited in the wild.
How severe is CVE-2026-21577?: Informational severity, with a CVSS score of 7.1, published 21 July 2026.
Which products and versions are affected?: Atlassian Confluence Data Center 9.0.1 to 9.5.4, 10.0.2 to 10.2.6.
Is there a fix for CVE-2026-21577?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-21577 attacked?: It is attacked over the network, in a network appliance.
Am I affected by CVE-2026-21577?: Check whether you run Atlassian Confluence Data Center at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A Denial of Service (DoS) vulnerability exists in Atlassian Confluence Data Center across multiple versions in the 9.x and 10.x branches. The flaw allows a remote, authenticated attacker with low privileges to exhaust system resources or otherwise disrupt the host services, leading to a temporary or indefinite loss of availability for the application. The vulnerability was identified through Atlassian's internal penetration testing program. Fixes have been backported to Long Term Support (LTS) releases, specifically versions 9.2.17 and 10.2.7.

Affected products

Atlassian Confluence Data Center 9.0.1 to 9.5.4, 10.0.2 to 10.2.6

Timeline

2026-07-08: other: Internal issue created in Atlassian Jira
2026-07-21: advisory: Security bulletin published by Atlassian
2026-07-21: disclosed: CVE-2026-21577 published to NVD

References

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