Is CVE-2021-26084 actively exploited?

Yes. Previdian tracks CVE-2021-26084 as a known exploited vulnerability. Confidence is confirmed.

What exploitation activity has Previdian observed?

Previdian has not yet recorded sensor-observed exploitation attempts for CVE-2021-26084. Our sensors continue to monitor for activity targeting this CVE.

Which versions are affected?

CVE-2021-26084 affects Atlassian Confluence Server, Confluence Data Center. Previdian lists 14 version rows; examples include unspecified to < 6.13.23, 6.14.0 to < unspecified, and unspecified to < 7.4.11.

Yes. CVE-2021-26084 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

CVE-2021-26084 Exploited in the Wild — Confluence

Q: How should organizations remediate it?

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

Q: Is it in CISA KEV?

Yes. CVE-2021-26084 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2021-26084 is an unauthenticated vulnerability affecting Atlassian Confluence Server, Confluence Data Center. In affected versions of Confluence Server and Data Center, an OGNL injection vulnerability exists that...

Is it exploited?

Yes. Previdian tracks this CVE as a known exploited vulnerability. Confidence is confirmed. Listed in CISA KEV. Also confirmed by third-party sources.

Who is affected?

Atlassian / Confluence Server affected before 6.13.23.

What should we do?

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

Overview

Confluence Server

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.

Vendor Product Affected Status

Atlassian Affected

Confluence Server

Before 6.13.23 Before unspecified Before 7.4.11 Before 7.11.6 Before 7.12.5

Affected

Atlassian Affected

Confluence Data Center

Before 6.13.23 Before unspecified Before 7.4.11 Before 7.11.6 Before 7.12.5

Affected

Published: 30 Aug 2021
Exploitation Reported: 03 Nov 2021
Attack vector: Remote
Complexity: Low
Privileges: None
User interaction: None

CVE References

CVE Record CVE.org · CVE Record https://www.cve.org/CVERecord?id=CVE-2021-26084
jira.atlassian.com/browse/CONFSERVER-67940 jira.atlassian.com · CVE Record https://jira.atlassian.com/browse/CONFSERVER-67940
packetstormsecurity.com/files/167449/Atlassian-Confluence-Namespace-... packetstormsecurity.com · CVE Record http://packetstormsecurity.com/files/167449/Atlassian-Confluence-Name...

Exploitation evidence

Why Previdian marks this CVE as exploited

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploited in the wild

CISA

Recorded 03 Nov 2021

A trusted third party reported exploitation.

Used in malware

CISA

Recorded 03 Nov 2021

Malware families have been linked to exploitation of this CVE.

Proof of concept available

GitHub

Recorded 31 Aug 2021

Public scanner or PoC coverage increases practical exploitability.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the Previdian Pro API.

Learn about Pro API access

Source	Added
CISA First	2021-11-03 00:00 UTC
The Shadowserver	2026-06-01 00:00 UTC

Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets
User-Agents
Callback hosts: 0; 0; 0

Request targets and User-Agents available in Pro. Callback host details available in Enterprise.

Scanner coverage

Metasploit template detected 28 Apr 2025.

View Metasploit template

Virtual patch status

No Previdian virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

Learn about virtual patches →

Scanner Artifacts

Scanner and exploit-framework references linked to this CVE.

Scanner	Reference	Detected
Metasploit	https://github.com/rapid7/metasploit-framework/blob/master/modules/exploits/multi/http/atlassian_confluence_webwork_ognl_injection.rb	28 Apr 2025
Nuclei	https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2021/CVE-2021-26084.yaml	25 Apr 2025

Risk and context

Severity, weaknesses, and research context

CVSS v3.1

9.8 Critical

Potential damage if exploited. Separate from whether attackers are using it.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS

100.0%

Estimated chance of exploitation in the next 30 days. Previdian's warning comes from evidence, not this score.

Weaknesses

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

All CVSS Scores

CVSS v3.1 9.8 Critical

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS v2.0 7.5 High

AV:N/AC:L/Au:N/C:P/I:P/A:P

Potential Proof of Concepts

These PoCs are unverified and could contain malware. Use at your own risk.

1ZRR4H/CVE-2021-26084

github · Created 2021-09-07 01:15:16 UTC · 30 stars · AI assessment 85%

Atlassian Confluence CVE-2021-26084 one-liner mass checker

0xf4n9x/CVE-2021-26084

github · Created 2021-09-01 09:50:26 UTC · 69 stars · AI assessment 90%

CVE-2021-26084 Remote Code Execution on Confluence Servers

hev0x/CVE-2021-26084_Confluence

github · Created 2021-09-01 07:15:17 UTC · 309 stars · AI assessment 90%

Confluence Server Webwork OGNL injection

dinhbaouit/CVE-2021-26084

github · Created 2021-09-01 00:50:30 UTC · 54 stars · AI assessment 90%

alt3kx/CVE-2021-26084_PoC

github · Created 2021-08-31 23:33:44 UTC · 54 stars · AI assessment 85%

Confluence Server - Remote Code Execution

nuclei · Created Unknown

atlassian_confluence_webwork_ognl_injection

metasploit · Created Unknown

Metasploit module for CVE-2021-26084

Timeline

From disclosure to observed exploitation

01 Jun 2026
00:00 UTC

KEV confirmed by The Shadowserver

Exploitation attested by an external source
28 Apr 2025
15:02 UTC

Metasploit module available

Exploit module available
25 Apr 2025
00:00 UTC

Nuclei template available

Scanner coverage available
03 Nov 2021
00:00 UTC

Added to CISA KEV

Listed in the CISA Known Exploited Vulnerabilities catalog
03 Nov 2021
00:00 UTC

First public exploitation report

Exploit observed in malware
31 Aug 2021
23:33 UTC

Public PoC available

Public proof-of-concept code published
30 Aug 2021
06:30 UTC

CVE published

Vulnerability disclosed publicly
25 Jan 2021
00:00 UTC

CVE ID reserved

Identifier reserved by the CNA

Pro API

Automate this intelligence

Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

Start 14-day Pro trial Read API docs

Evidence confidence and provenance
First-party sensor telemetry
PoC and scanner references
Affected versions and enrichment
Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2021-26084

Sample API response

{
  "cve_id": "CVE-2021-26084",
  "confidence": "Confirmed",
  "cvss_score": 9.8,
  "cvss_estimated": false,
  "epss_score": 0.99999,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": false
  },
  "sensor_telemetry": { "attempts": 0, "sensors": 0 }
}

CVE-2021-26084

Confluence Server

Tags

CVE References

Exploited in the wild

Used in malware

Proof of concept available

Known exploited vulnerability sources

Observed signals

Scanner coverage

Virtual patch status

Scanner Artifacts

Weaknesses

All CVSS Scores

Potential Proof of Concepts

KEV confirmed by The Shadowserver

Metasploit module available

Nuclei template available

Added to CISA KEV

First public exploitation report

Public PoC available

CVE published

CVE ID reserved

Automate this intelligence