# CVE-2026-21580: Cross-site scripting in Confluence Data Center

> Unauthenticated attackers can execute arbitrary JavaScript and escalate privileges in Confluence Data Center and Server via stored XSS.

- **Severity:** High 8.6 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 18 Aug 2026
- **Updated:** 21 Aug 2026
- **Also known as:** GHSA-88w8-m3v4-74h6

## What is CVE-2026-21580?

CVE-2026-21580 is a high-severity cross-site scripting vulnerability in Atlassian Confluence Data Center, published on 18 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-21580?


## How do I fix CVE-2026-21580?

No fix has been published for CVE-2026-21580 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-21580 being exploited?

There is no known exploitation of CVE-2026-21580 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-21580 and fix it if it is affected.

What it is: CVE-2026-21580 is a high-severity cross-site scripting vulnerability in Atlassian Confluence Data Center, published on 18 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-21580 in the wild and no public exploit code.

Affected product: Atlassian Confluence Data Center. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-21580/ (Markdown: https://insights.sbomify.com/CVE-2026-21580/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-21580
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-21580
- OSV: https://osv.dev/vulnerability/CVE-2026-21580

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-21580/
Summaries are generated and may contain mistakes; the official description above is the record.