CVE-2021-26084

Exp

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.

Published: 2021-08-30 Last update: 2025-10-24 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-26084 is rated Critical Active Threat (99.2/100): CVSS Critical severity, with high exploitation likelihood (EPSS 94.44%, 100th percentile). CISA KEV confirms active exploitation (added 2021-11-03) affecting Atlassian / Confluence Server and Data Center. a weakness (CWE-917) Unauthenticated remote administrative access may be possible. The CISA remediation deadline has passed—treat as an emergency patch priority.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

CISA KEV Record for CVE-2021-26084

Name: Atlassian Confluence Server and Data Center Object-Graph Navigation Language (OGNL) Injection Vulnerability · CISA KEV detail

Exploit added: 2021-11-03

Action due: 2021-11-17

Required action: Apply updates per vendor instructions.

Public exploit references (Exploit-DB) for CVE-2021-26084

EDB-ID Source Kind Published Link
50243 exploit_db edb 2021-09-01 Exploit-DB ↗
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2021-26084

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-02-20 94.47% 94.44% -0.03%
2 2026-02-18 94.44% 94.47% +0.03%
3 2025-12-20 — 94.44% —

Full EPSS history (30 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-26084

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 134c704f-9b21-4f2e-91b3-4a467353bcc0
7.5 2.0 HIGH
AV:N/AC:L/Au:N/C:P/I:P/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 6.4 [email protected]

Weakness enumeration for CVE-2021-26084

Affected software / configurations for CVE-2021-26084

Vendor Product Version Raw CPE
atlassian confluence_data_center < 6.13.23 cpe:2.3:a:atlassian:confluence_data_center:*:*:*:*:*:*:*:*
atlassian confluence_data_center >= 6.14.0, < 7.4.11 cpe:2.3:a:atlassian:confluence_data_center:*:*:*:*:*:*:*:*
atlassian confluence_data_center >= 7.5.0, < 7.11.6 cpe:2.3:a:atlassian:confluence_data_center:*:*:*:*:*:*:*:*
atlassian confluence_data_center >= 7.12.0, < 7.12.5 cpe:2.3:a:atlassian:confluence_data_center:*:*:*:*:*:*:*:*
atlassian confluence_server < 6.13.23 cpe:2.3:a:atlassian:confluence_server:*:*:*:*:*:*:*:*
atlassian confluence_server >= 6.14.0, < 7.4.11 cpe:2.3:a:atlassian:confluence_server:*:*:*:*:*:*:*:*
atlassian confluence_server >= 7.5.0, < 7.11.6 cpe:2.3:a:atlassian:confluence_server:*:*:*:*:*:*:*:*
atlassian confluence_server >= 7.12.0, < 7.12.5 cpe:2.3:a:atlassian:confluence_server:*:*:*:*:*:*:*:*

References for CVE-2021-26084

cvelogic Threat Intelligence