CVE-2021-26084
CriticalExploitedPublic exploitIn 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.
Published Sep 14, 2021 · Updated Dec 16, 2025 · Also known as TR-21-0704
Key Facts
Patch immediately- CVE-2021-26084 is a critical-severity vulnerability (CVSS 9.8 v3.1) affecting Confluence Data Center (Atlassian), Confluence Server (Atlassian).
- It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Sep 8, 2021 and is known to be used in ransomware campaigns. Public exploit code is available.
- EPSS estimates a 100% probability of exploitation in the next 30 days.
- Fixed versions are available, including Confluence Data Center 6.13.23, Confluence Data Center 7.11.6, Confluence Data Center 7.12.5.
- Brandefense priority: patch immediately, because it is listed as exploited in the wild.
CVSS v3.1
9.8
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS (30-day exploit likelihood)
100%
Higher than 99.9% of all scored CVEs
Exploited in the wild
Yes
4 catalog listings, used by ransomware
Public exploit code
Available
Proof-of-concept or weaponized module
Get the full CVE-2021-26084 brief as a PDF
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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.
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| CISA KEV | Nov 3, 2021 | Nov 17, 2021 | Known |
| Industry KEV feed | Sep 8, 2021 | Nov 17, 2021 | Known |
| CIRCL KEV | Nov 3, 2021 | Nov 17, 2021 | Known |
| ENISA EUVD | Nov 3, 2021 | n/a | Not reported |
Required action: Apply updates per vendor instructions.
Affected Products
4 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| Confluence Data CenterAtlassian | >= unspecified | 6.13.23 |
| Confluence ServerAtlassian | >= unspecified | 6.13.23 |
Patched Releases
Confluence Data Center
6.13.23, 7.11.6, 7.12.5, 7.4.11, unspecified
Confluence Server
6.13.23, 7.11.6, 7.12.5, 7.4.11, unspecified
Timeline
Added to Industry KEV feed
Sep 8, 2021
Publicly disclosed
Sep 14, 2021
Added to CISA KEV
Nov 3, 2021
Added to CIRCL KEV
Nov 3, 2021
Added to ENISA EUVD
Nov 3, 2021
Last updated
Dec 16, 2025
Weakness Type
- CWE-917 Improper Neutralization of Special Elements used in an Expression Language Statement ('Expression Language Injection')
References
- advisoryhttps://confluence.atlassian.com/doc/confluence-security-advisory-2021-08-25-1077906215.html
- advisoryhttps://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-26084
- advisoryhttps://securityaffairs.co/wordpress/121746/security/enterprise-nfvis-critical-flaw.html?utm_source=rss&utm_medium=rss&utm_campaign=enterprise-nfvis-critical-flaw
- advisoryhttps://threatpost.com/cisco-patches-critical-authentication-bug-with-public-exploit/169146/
- advisoryhttps://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-nfvis-g2DMVVh
FAQ
Common Questions.
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.
Affected: Confluence Data Center (Atlassian) versions >= unspecified; Confluence Server (Atlassian) versions >= unspecified. The full list is in the CVE brief.
It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Sep 8, 2021 and is known to be used in ransomware campaigns.
Yes. It was added on Nov 3, 2021 with a federal remediation due date of Nov 17, 2021.
Public exploit code is available.
Fixed versions are available, including Confluence Data Center 6.13.23, Confluence Data Center 7.11.6, Confluence Data Center 7.12.5.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
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