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

- Exploited (CISA KEV): yes, added 2021-11-03, known ransomware use
- Published: 2021-08-30
- CVSS: 9.8 CRITICAL (v3.1)
- EPSS: 100.0% (100th percentile)
- CWE: CWE-917

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.

## Edge WAF coverage (claimed by vendors, not measured)

| Vendor | Status | First rule | Days after publication |
|---|---|---|---|
| Cloudflare | Blocks by default | 2025-12-18 | — |
| AWS | No public claim | — | — |
| Microsoft Azure | No public claim | — | — |
| Google Cloud | Before feed history | — | — |
| Fastly | Before feed history | — | — |
| F5 | Before feed history | — | — |
| Akamai | No public source | — | — |
| OWASP CRS | Before feed history | — | — |

### Cloudflare

- 2025-12-18 · updated · rule 6429f7386b1546cf9dfce631be5ec20c · default Block
  > Atlassian Confluence - Code Injection - CVE:CVE-2021-26084 - Beta. Previous action: Log. New action: Block. This rule is merged into the original rule "Atlassian Confluence - Code Injection - CVE:CVE-2021-26084" (ID: ...69e0b97a )
  Source: https://developers.cloudflare.com/changelog/post/2025-12-18-waf-release/

## Our test (measured)

- OWASP Core Rule Set 4.25.0, paranoia level 1, anomaly threshold 5, default CRS settings: blocked (1 of 1 requests blocked), template CVE-2021-26084, 2026-11-02
- OWASP Core Rule Set 4.25.0, paranoia level 2, anomaly threshold 5, default CRS settings: blocked (1 of 1 requests blocked), template CVE-2021-26084, 2026-11-02

"No public claim" means no vendor statement names this CVE; "Before feed history" means the CVE is older than the vendor feed. In both cases generic rules may still block it.

HTML: https://cve.vigilbase.com/cve/CVE-2021-26084 · JSON: https://cve.vigilbase.com/api/v1/cves/CVE-2021-26084