CVE-2026-21577
Atlassian Confluence Data Center Denial of Service Vulnerability
Description
This High severity DoS (Denial of Service) vulnerability was introduced in 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 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 9.2.17 Confluence Data Center 10.2: Upgrade to a release greater than or equal to 10.2.7 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.
INFO
Published Date :
July 21, 2026, 6:16 p.m.
Last Modified :
July 22, 2026, 7:16 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 4.0 | HIGH | [email protected] |
Solution
- Upgrade to the latest version of Confluence Data Center.
- Upgrade to a supported fixed version if latest is not possible.
- Consult release notes for specific version details.
- Download software from the official Atlassian download center.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-21577.
| URL | Resource |
|---|---|
| https://confluence.atlassian.com/pages/viewpage.action?pageId=1821999345 | |
| https://jira.atlassian.com/browse/CONFSERVER-104334 |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-21577 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-21577
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-21577 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-21577 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jul. 22, 2026
Action Type Old Value New Value Added CWE CWE-400 Added SSVC {'id': 'CVE-2026-21577', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-07-22T18:32:38.139315Z'} -
New CVE Received by [email protected]
Jul. 21, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'Atlassian', 'product': 'Confluence Data Center', 'versions': [{'status': 'affected', 'version': '10.2.0 to 10.2.6'}, {'status': 'affected', 'version': '10.1.0 to 10.1.2'}, {'status': 'affected', 'version': '10.0.2 to 10.0.3'}, {'status': 'affected', 'version': '9.5.1 to 9.5.4'}, {'status': 'affected', 'version': '9.4.0 to 9.4.1'}, {'status': 'affected', 'version': '9.3.1 to 9.3.2'}, {'status': 'affected', 'version': '9.2.0 to 9.2.15'}, {'status': 'affected', 'version': '9.1.0 to 9.1.1'}, {'status': 'affected', 'version': '9.0.1 to 9.0.3'}, {'status': 'unaffected', 'version': '10.2.7 to 10.2.14'}, {'status': 'unaffected', 'version': '9.2.17 to 9.2.22'}]}] Added Description This High severity DoS (Denial of Service) vulnerability was introduced in 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 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 9.2.17 Confluence Data Center 10.2: Upgrade to a release greater than or equal to 10.2.7 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. Added CVSS V4.0 AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added Reference https://confluence.atlassian.com/pages/viewpage.action?pageId=1821999345 Added Reference https://jira.atlassian.com/browse/CONFSERVER-104334