CVE-2026-21577: DoS (Denial of Service) in Atlassian Confluence Data Center
CVE-2026-21577 is a high severity Denial of Service (DoS) vulnerability affecting multiple versions of Atlassian Confluence Data Center. It allows an authenticated attacker to disrupt service availability by causing resource unavailability on the host. The vulnerability impacts specific versions from 9.0.1 through 10.2.0. Atlassian recommends upgrading to fixed versions 9.2.17 or later for the 9.2.x line, and 10.2.7 or later for the 10.2.x line to mitigate this issue.
AI Analysis
Technical Summary
This vulnerability (CVE-2026-21577) in Atlassian Confluence Data Center versions 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 allows an authenticated attacker to cause a Denial of Service (DoS) by making a resource unavailable, disrupting the service for legitimate users. The CVSS 4.0 base score is 7.1, indicating high severity. The vulnerability was discovered through Atlassian's penetration testing program. Atlassian advises upgrading to versions >=9.2.17 or >=10.2.7 where the issue is fixed. No cloud service is involved, and no known exploits in the wild have been reported.
Potential Impact
An authenticated attacker can cause temporary or indefinite disruption of service availability on the affected Confluence Data Center hosts, leading to denial of service for legitimate users. This impacts the reliability and accessibility of the Confluence Data Center application until the issue is remediated.
Mitigation Recommendations
Atlassian recommends upgrading affected Confluence Data Center instances to fixed versions: 9.2.17 or later for the 9.2.x branch, and 10.2.7 or later for the 10.2.x branch. If upgrading to the latest version is not possible, ensure at least these minimum fixed versions are applied. Patch status is confirmed by vendor advisory. No other mitigations are specified.
CVE-2026-21577: DoS (Denial of Service) in Atlassian Confluence Data Center
Description
CVE-2026-21577 is a high severity Denial of Service (DoS) vulnerability affecting multiple versions of Atlassian Confluence Data Center. It allows an authenticated attacker to disrupt service availability by causing resource unavailability on the host. The vulnerability impacts specific versions from 9.0.1 through 10.2.0. Atlassian recommends upgrading to fixed versions 9.2.17 or later for the 9.2.x line, and 10.2.7 or later for the 10.2.x line to mitigate this issue.
CVSS v4.0
Score 7.1high
Affected software
pkg:maven/com.atlassian.confluence/confluence-data-centerRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability (CVE-2026-21577) in Atlassian Confluence Data Center versions 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 allows an authenticated attacker to cause a Denial of Service (DoS) by making a resource unavailable, disrupting the service for legitimate users. The CVSS 4.0 base score is 7.1, indicating high severity. The vulnerability was discovered through Atlassian's penetration testing program. Atlassian advises upgrading to versions >=9.2.17 or >=10.2.7 where the issue is fixed. No cloud service is involved, and no known exploits in the wild have been reported.
Potential Impact
An authenticated attacker can cause temporary or indefinite disruption of service availability on the affected Confluence Data Center hosts, leading to denial of service for legitimate users. This impacts the reliability and accessibility of the Confluence Data Center application until the issue is remediated.
Mitigation Recommendations
Atlassian recommends upgrading affected Confluence Data Center instances to fixed versions: 9.2.17 or later for the 9.2.x branch, and 10.2.7 or later for the 10.2.x branch. If upgrading to the latest version is not possible, ensure at least these minimum fixed versions are applied. Patch status is confirmed by vendor advisory. No other mitigations are specified.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- atlassian
- Date Reserved
- 2026-01-01T00:00:40.721Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a5faf7c2a4a8d59898322a7
Added to database: 07/21/2026, 17:42:20 UTC
Last enriched: 07/30/2026, 09:09:44 UTC
Last updated: 08/26/2026, 10:52:07 UTC
Views: 152
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.