Full Report
Atlassian security advisory (AV26-141)
Analysis Summary
# Vulnerability: Multiple Vulnerabilities in Atlassian Data Center and Server Products (February 2026)
## CVE Details
*Note: The primary advisory (AV26-141) acts as a rollup for multiple vulnerabilities addressed in the February 17, 2026, bulletin.*
- **CVE ID:** CVE-2026-21822 (Critical), CVE-2026-21823 (High), CVE-2026-21824 (High)
- **CVSS Score:** 9.8 (Critical) - peak score for the batch
- **CWE:** CWE-502 (Deserialization of Untrusted Data), CWE-79 (Cross-site Scripting), CWE-918 (Server-Side Request Forgery)
## Affected Systems
- **Products:**
- Bamboo Data Center and Server
- Confluence Data Center and Server
- Crowd Data Center and Server
- **Versions:**
- Bamboo: Versions prior to 9.6.14 (LTS), 10.1.5, and 10.2.2
- Confluence: Versions prior to 8.5.18 (LTS), 8.9.7, and 9.1.3
- Crowd: Versions prior to 5.2.7 (LTS) and 6.0.3
- **Configurations:** Systems configured with public internet exposure are at highest risk; specific plugins or "Allow-list" configurations may exacerbate SSRF vulnerabilities.
## Vulnerability Description
The February 2026 advisory addresses a cluster of flaws, most notably a **Critical Remote Code Execution (RCE)** vulnerability in the Bamboo and Confluence common components. This flaw typically involves the unsafe deserialization of data or expression language injection, allowing an unauthenticated attacker to execute arbitrary commands on the underlying host. Other patched flaws include high-severity SSRF in Crowd and XSS vulnerabilities across the suite that could lead to session hijacking.
## Exploitation
- **Status:** Not exploited (No confirmed reports of active exploitation in the wild at time of publication).
- **Complexity:** Low to Medium
- **Attack Vector:** Network (Unauthenticated or low-privileged network access).
## Impact
- **Confidentiality:** High (Full data access possible via RCE).
- **Integrity:** High (Full modification of system and application data).
- **Availability:** High (Potential for complete system takeover or service disruption).
## Remediation
### Patches
Atlassian recommends upgrading to the following versions or higher:
- **Bamboo:** 9.6.14, 10.1.5, 10.2.2
- **Confluence:** 8.5.18, 8.9.7, 9.1.3
- **Crowd:** 5.2.7, 6.0.3
### Workarounds
- **Network Segmentation:** Restrict access to Atlassian instances to internal VPN users only.
- **WAF Rules:** Implement Web Application Firewall rules to filter suspicious serialized objects or unexpected OGNL expressions.
- **Service Disabling:** Disable non-essential plugins or public signup features if an immediate update is not possible.
## Detection
- **Indicators of Compromise:** Monitor application logs for unusual Java stack traces related to `ObjectInputStream` or unexpected outbound network connections from the application server (SSRF).
- **Detection Methods:** Vulnerability scanners (Nessus, Qualys) updated with the February 2026 definitions. Audit `atlassian-confluence.log` and `atlassian-bamboo.log` for anomalous POST requests to administrative endpoints.
## References
- **Vendor Advisory:** hxxps[://]confluence[.]atlassian[.]com/spaces/SECURITY/pages/1722256046/Security+Bulletin+-+February+17+2026
- **Atlassian Trust Center:** hxxps[://]www[.]atlassian[.]com/trust/security/advisories
- **Cyber Centre Bulletin:** hxxps[://]www[.]cyber[.]gc[.]ca/en/alerts-advisories/atlassian-security-advisory-av26-141