Atlassian Jira Server and Data Center Path Traversal Information Disclosure Vulnerability (CVE-2021-26086) Security Advisory
Executive & SecOps Summary
SECOPS ASSESSMENTAtlassian Jira Server and Data Center versions before 8.5.14, 8.6.0 before 8.13.6, and 8.14.0 before 8.16.1
Unauthenticated remote attackers can exploit a path traversal vulnerability to read sensitive configuration files, such as '/WEB-INF/web.xml'
Immediately upgrade Jira instances to the patched versions (8.5.14, 8.13.6, 8.16.1, or later) and apply WAF access control rules
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
Following Atlassian's official advisory, upgrade your Jira instances to a secure version (8.5.14, 8.13.6, 8.16.1, or later).
# Navigate to installation directory and perform backup
tar -czvf jira_backup_$(date +%F).tar.gz /opt/atlassian/jira /var/atlassian/application-data/jira
# Download and run the installer for a secure LTS release (e.g., 8.13.6)
wget https://www.atlassian.com/software/jira/downloads/binary/atlassian-jira-software-8.13.6-x64.bin
chmod +x atlassian-jira-software-8.13.6-x64.bin
sudo ./atlassian-jira-software-8.13.6-x64.bin2. Temporary Workaround & Hardening Configuration
If an immediate upgrade is not feasible, block external access to the '/WEB-INF/' directory using a reverse proxy such as Nginx.
# Add the following block to your Nginx configuration to block unauthorized access
server {
listen 80;
server_name jira.yourdomain.local;
location ~* /WEB-INF/ {
deny all;
return 403;
}
location / {
proxy_pass http://localhost:8080;
proxy_set_header Host $host;
}
}3. Log Audit & IoC Verification Commands
Inspect Jira access logs to identify potential exploitation attempts targeting the '/WEB-INF/' path.
# Search Jira access logs for unauthorized WEB-INF access attempts
grep -i 'WEB-INF' /var/atlassian/application-data/jira/log/atlassian-jira-http-access*.logBlock Exploits Instantly with Managed Virtual Patching Rules
Can't patch production immediately? Deploy managed WAF rules at the edge to intercept RCE, SQLi, and deserialization payloads before they hit your origin server.
Technical Root Cause & Exploitation Mechanics
1. Vulnerability Overview & Root Cause
This vulnerability (CVE-2021-26086) is a path traversal flaw (CWE-22) in Atlassian Jira Server and Data Center. Due to insufficient input validation, unauthenticated remote attackers can bypass access controls to traverse directories and read restricted files within the application structure, specifically targeting the '/WEB-INF/web.xml' endpoint.
2. Exploitation Mechanics & Attack Scenario
An attacker sends a crafted HTTP GET request designed to exploit servlet container path normalization behaviors. By bypassing standard URL filtering mechanisms, the attacker forces the application to resolve the path to the protected '/WEB-INF/web.xml' file and return its contents. This vulnerability is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, indicating active exploitation in the wild.
3. Infrastructure & Business Impact
Exposure of the '/WEB-INF/web.xml' file leaks critical application metadata, including servlet mappings, security filters, and session configurations. This information significantly reduces the barrier for attackers to orchestrate subsequent attacks, such as authentication bypass or remote code execution (RCE), posing a severe threat to enterprise infrastructure.
Official Vendor Advisories & References
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.
Frequently Asked SecOps Questions (CVE-2021-26086)
FAQQ1. How critical is CVE-2021-26086 and is it actively exploited in the wild?
CVE-2021-26086 is rated CVSS 5.3 (MEDIUM) with a 30-day EPSS exploitation probability of 100.0%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2021-26086?
Primary impacted vendors include atlassian across jira_server, jira_data_center. Scope summary: Atlassian Jira Server and Data Center: - Versions before 8.5.14 - Versions 8.6.0 before 8.13.6 - Versions 8.14.0 before 8.16.1
Q3. What temporary mitigations or workarounds exist for CVE-2021-26086 before patching?
[Mitigation] Immediately upgrade Jira instances to the patched versions (8.5.14, 8.13.6, 8.16.1, or later) and apply WAF access control rules Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.
Generate an Internal Engineering Notice or CISO Report for CVE-2021-26086
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