# CVE-2021-26084: Atlassian Confluence Server and Data Center Object-Graph Navigation Language (OGNL) Injection

> Unauthenticated attackers can execute arbitrary code on Confluence Server or Data Center instances via OGNL injection.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Yes, since 3 Nov 2021 (CISA KEV), used in ransomware
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 30 Aug 2021
- **Updated:** 16 Dec 2025
- **Also known as:** GHSA-855c-xp53-5fp2

## What is CVE-2021-26084?

CVE-2021-26084 is a critical code injection vulnerability in Atlassian Confluence Data Center, published on 30 Aug 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In affected versions of Confluence Server and Data Center, an OGNL injection vulnerability exists that would allow an unauthenticated attacker to execute arbitrary code on a Confluence Server or Data Center instance. The affected versions are before version 6.13.23, from version 6.14.0 before 7.4.11, from version 7.5.0 before 7.11.6, and from version 7.12.0 before 7.12.5.

Weakness: CWE-917 (Improper Neutralization of Special Elements used in an Expression Language Statement)

## Which versions are affected by CVE-2021-26084?

It affects 2 products.


Products: Atlassian Confluence Data Center, Atlassian Confluence Server.

## How do I fix CVE-2021-26084?

No fix has been published for CVE-2021-26084 yet. Limit exposure of the affected software until one is available. US federal agencies must fix it by 17 Nov 2021.

## Is CVE-2021-26084 being exploited?

Yes. Attackers have exploited CVE-2021-26084 in the wild since at least 3 Nov 2021, including in ransomware campaigns.

Public exploit code:

- Confluence Server Webwork OGNL injection (github_poc): https://github.com/hev0x/CVE-2021-26084_Confluence
- CVE-2021-26084 Remote Code Execution on Confluence Servers (github_poc): https://github.com/0xf4n9x/CVE-2021-26084
- https://github.com/alt3kx/CVE-2021-26084_PoC (github_poc): https://github.com/alt3kx/CVE-2021-26084_PoC
- https://github.com/dinhbaouit/CVE-2021-26084 (github_poc): https://github.com/dinhbaouit/CVE-2021-26084
- Atlassian Confluence CVE-2021-26084  one-liner mass checker (github_poc): https://github.com/1ZRR4H/CVE-2021-26084
- CVE-2021-26084 - Confluence Pre-Auth RCE | OGNL injection  (github_poc): https://github.com/crowsec-edtech/CVE-2021-26084

## Other vulnerabilities in Atlassian Confluence Data Center

- [CVE-2023-22527](https://insights.sbomify.com/CVE-2023-22527/): Atlassian Confluence Data Center and Server Template Injection (critical 10.0, exploited in the wild)
- [CVE-2023-22518](https://insights.sbomify.com/CVE-2023-22518/): Atlassian Confluence Data Center and Server Improper Authorization (critical 10.0, exploited in the wild)
- [CVE-2023-22515](https://insights.sbomify.com/CVE-2023-22515/): Atlassian Confluence Data Center and Server Broken Access Control (critical 10.0, exploited in the wild)
- [CVE-2022-26134](https://insights.sbomify.com/CVE-2022-26134/): Atlassian Confluence Server and Data Center Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2021-26085](https://insights.sbomify.com/CVE-2021-26085/): Atlassian Confluence Server Pre-Authorization Arbitrary File Read (medium 5.3, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-26084 and fix it if it is affected.

What it is: CVE-2021-26084 is a critical code injection vulnerability in Atlassian Confluence Data Center, published on 30 Aug 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: Yes. Attackers have exploited CVE-2021-26084 in the wild since at least 3 Nov 2021, including in ransomware campaigns.

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-2021-26084/ (Markdown: https://insights.sbomify.com/CVE-2021-26084/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-26084
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-26084
- OSV: https://osv.dev/vulnerability/CVE-2021-26084

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-26084/
Summaries are generated and may contain mistakes; the official description above is the record.