Secuno
ENNL
Book demo

CVE-2021-26084

Atlassian Confluence Server and Data Center Object-Graph Navigation Language (OGNL) Injection

9.8 CRITICALActively exploited (CISA KEV)Used in ransomwarePublic exploitEPSS 100.0%
  1. Published30 Aug 2021
  2. Added to CISA KEV3 Nov 2021
  3. Remediation due17 Nov 2021
Actively exploited (CISA KEV)

Atlassian Confluence Server and Data Server contain an Object-Graph Navigation Language (OGNL) injection vulnerability that may allow an unauthenticated attacker to execute code.

Added to KEV: 3 Nov 2021Federal remediation due: 17 Nov 2021Used in ransomware

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.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

Atlassian Confluence Data Center≥ 6.14.0 < 7.4.11 · ≥ 7.12.0 < 7.12.5 · ≥ 7.5.0 < 7.11.6 · < 6.13.23
Atlassian Confluence Server≥ 6.14.0 < 7.4.11 · ≥ 7.12.0 < 7.12.5 · ≥ 7.5.0 < 7.11.6 · < 6.13.23

Remediation

Fixed in
Atlassian Confluence Data Center≥ 7.4.11
Atlassian Confluence Server≥ 7.4.11

References

Related CVEs

Recent high-severity vulnerabilities sharing a weakness type.

CVE-2026-1047119.8
Improper neutralization of special elements used in an expression language statement…
CVE-2026-878309.1
In the StAX streaming WS-SecurityPolicy validator, certain relative or unsupported…
CVE-2026-524399.8
An issue in xiandafu beetl 3.20.2 allows a remote attacker to execute arbitrary code…
CVE-2026-655918.8
n8n contains a sanitizer bypass vulnerability in the legacy expression evaluator's…
CVE-2026-115619.8
Improper neutralization of special elements used in an expression language statement…
CVE-2026-417298.1
Spring Data REST is vulnerable to SpEL expression injection through map-typed…

Frequently asked

Is CVE-2021-26084 being actively exploited?

Yes. CVE-2021-26084 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added 3 Nov 2021. It has been used in ransomware campaigns.

How severe is CVE-2021-26084?

CVE-2021-26084 has a CVSS 3.1 base score of 9.8, rated critical. EPSS estimates a 100.0% probability of exploitation.

Which products are affected by CVE-2021-26084?

Affected products include Atlassian Confluence Data Center, Atlassian Confluence Server.

How do I fix CVE-2021-26084?

Upgrade affected software to a fixed version, for example Atlassian Confluence Data Center 7.4.11, Atlassian Confluence Server 7.4.11 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2021-26084 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. Because it is on the CISA KEV list, Secuno flags any affected asset as top-priority automatically. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

See how prioritisation worksBook a demo

Get Patch this first every Monday

Five vulnerabilities that matter this week, ranked on real exploitation. Plain language, one email, no spam.

You can unsubscribe with one click from every issue. We handle your details as described in our privacy policy.

Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.