Exploited CVEs / Atlassian / CVE-2021-26086
CVE-2021-26086
Atlassian Jira Server and Data Center Path Traversal Vulnerability. Exploitation in the wild is confirmed by CISA, not predicted. Federal agencies were required to remediate by 2024-12-03 (that deadline has passed); treat that date as the outer bound for your own environment. The fix is in the vendor advisory: Atlassian Security Advisories, linked below.
Actively exploited Atlassian Jira Server and Data Center vulnerability, Medium severity, CVSS 5.3. Added to the CISA KEV catalog 2024-11-12.
Risk summary
Updated July 26, 2026. Data refreshed on every build from MSRC, CISA KEV, and FIRST EPSS.
Senserva AI Opinion for CVE-2021-26086
A 100% EPSS score on a Medium Severity bug is the story here: this Atlassian Jira Server and Data Center path traversal only reads certain files like /WEB-INF/web.xml (CVSS 5.3), yet it is among the most exploited flaws on the internet and KEV-listed since 2024-11-12. Attackers harvest configuration details from these files to fingerprint and stage deeper attacks on Jira, which typically holds a company's project and credential-adjacent data. Self-hosted Jira instances exposed to the internet are scanned for this constantly.
Do this: Patch self-managed Jira Server and Data Center instances or shield them behind a VPN, and check access logs for WEB-INF request patterns.
AI-generated from public data, 2026-07-07. Verify against the vendor advisory before acting.
Senserva AI Opinion and rich prompt for CVE-2021-26086
Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.
Full tracking and change history for CVE-2021-26086
Published and last-revised dates are authoritative, from Microsoft MSRC (or the CISA KEV date-added). Senserva additionally records day-to-day changes from 2026-07-07, refreshed several times a day; the change count reflects that forward-only tracking.
CISA required action
Federal (BOD 22-01) remediation due date: 2024-12-03 (past due).
Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
Official fix for CVE-2021-26086
The authoritative fix and affected-version list are published by the vendor. Find the Jira Server and Data Center advisory on Atlassian Security Advisories.
Common questions about CVE-2021-26086
Is CVE-2021-26086 actively exploited?
Yes. CVE-2021-26086 was added to the CISA Known Exploited Vulnerabilities (KEV) catalog on 2024-11-12, which means exploitation in the wild has been confirmed, not predicted. Its EPSS 30-day exploitation probability is 100%.
What is the CISA deadline and required action for CVE-2021-26086?
CISA set the federal (BOD 22-01) remediation due date at 2024-12-03, which has passed; treat any unremediated system as overdue. The verbatim required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
What fixes CVE-2021-26086?
The authoritative fix is in the vendor advisory: see Atlassian Security Advisories for the patched Jira Server and Data Center versions and any workarounds. KEV listing makes this a fix-first item: patch it ahead of higher-CVSS issues nobody is exploiting.
Can I ask my own AI about CVE-2021-26086?
Yes. This page includes a free, ready-to-paste AI prompt containing CVE-2021-26086's key facts: severity, CVSS, EPSS, the KEV date, the CISA due date, and the required action. Copy it into Claude, ChatGPT, or Copilot; the data is refreshed twice a day (5 AM and 3 PM US Central).
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Authoritative references
Every actively exploited CVE, searchable with due dates and CSV export: the exploited-CVE tracker. The newest additions: exploited this week.
