What is CVE-2021-26086?

CVE-2021-26086 is a medium-severity vulnerability in Atlassian Jira Data Center, classified under Path Traversal. CVSS score: 5.3/10. Published 2021-08-16.

How severe is CVE-2021-26086?

Medium severity. CVSS v3 base score is 5.3 out of 10.

Is CVE-2021-26086 known to be exploited?

Yes. CVE-2021-26086 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2024-11-12), indicating it is being actively exploited. 49 public proof-of-concept repositories are indexed.

Path Traversal in Atlassian Jira Data Center

CVE-2021-26086

Affected versions of Atlassian Jira Server and Data Center allow remote attackers to read particular files via a path traversal vulnerability in the /WEB-INF/web.xml endpoint. The affected versions are before version 8.5.14, from version 8.6.0 before 8.13.6, and from version 8.14.0 before 8.16.1.

Vulnerability class: Path Traversal (Directory Traversal)

Published 2021-08-16 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N.

EPSS exploit prediction

EPSS: 1.000 (100.0th percentile), scored 2026-09-02.

Very high probability of exploitation in the next 30 days — among the top 0.1% most-likely-to-be-exploited CVEs. 100th percentile — 100.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

The 30-day trend appears once there are two daily scores.

Affected products

Atlassian Jira Data Center — versions unspecified, 8.6.0, 8.14.0
Atlassian Jira Data Center
Atlassian Jira Server — versions unspecified, 8.6.0, 8.14.0
Atlassian Jira Server

Weakness classification (CWE)

CWE-22 — Path Traversal

CISA KEV (Known Exploited Vulnerabilities)

This CVE is on the CISA KEV catalog, added on 2024-11-12. CISA KEV inclusion means CISA has confirmed in-the-wild exploitation; US federal agencies are required to remediate within a published due date.

BOD 22-01 due date: 2024-12-03.

Required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

Public proof-of-concept exploits

References

jira.atlassian.com/browse/JRASERVER-72695 (Issue Tracking, Vendor Advisory)
packetstormsecurity.com/files/164405/Atlassian-Jira-Server-Data-Center-8.4.0-Fi… (Exploit, VDB Entry, Third Party Advisory)
134c704f-9b21-4f2e-91b3-4a467353bcc0 (US Government Resource)

Frequently asked questions

What is CVE-2021-26086?: CVE-2021-26086 is a medium-severity vulnerability in Atlassian Jira Data Center, classified under Path Traversal. CVSS score: 5.3/10. Published 2021-08-16.
How severe is CVE-2021-26086?: Medium severity. CVSS v3 base score is 5.3 out of 10.
Is CVE-2021-26086 known to be exploited?: Yes. CVE-2021-26086 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2024-11-12), indicating it is being actively exploited. 49 public proof-of-concept repositories are indexed.