Critical Atlassian Bamboo RCE Flaw CVE-2024-1591 Lets Attackers Inject Commands

Key Takeaways

• Atlassian has issued urgent security advisories for its Bamboo Data Center and Server products.
• A critical OS command injection vulnerability (CVE-2026-21571) could allow remote code execution, while a high-severity denial-of-service flaw (CVE-2026-33871) also requires attention.
• Multiple versions of Bamboo are impacted, including LTS branches.
• Immediate patching is strongly recommended to mitigate severe risks to CI/CD pipelines and underlying server infrastructure.

Atlassian has disclosed two critical security vulnerabilities affecting its Bamboo Data Center and Server products, prompting an urgent call for administrators to apply patches. The most severe of these is a critical OS command injection flaw, alongside a high-severity denial-of-service issue stemming from a third-party dependency.

Critical OS Command Injection Poses Severe Risk (CVE-2026-21571)

The more pressing of the two, identified as CVE-2026-21571, has been assigned a CVSS score of 9.4, classifying it as critical. This vulnerability affects numerous versions of Bamboo Data Center and Server.

Categorized as an OS Command Injection, this flaw could enable a remote attacker to execute arbitrary operating system commands on the server hosting Bamboo. Such an exploit could lead to a complete compromise of the system, facilitate lateral movement within the network, or result in the exfiltration of sensitive data.

The following Bamboo versions are susceptible to CVE-2026-21571:

• 12.1.0 to 12.1.3 (LTS)
• 12.0.0 to 12.0.2
• 11.0.0 to 11.0.8
• 10.2.0 to 10.2.16 (LTS)
• 10.1.0 to 10.1.1
• 10.0.0 to 10.0.3
• 9.6.2 to 9.6.24 (LTS)

Atlassian advises upgrading to version 12.1.6 (LTS) for Data Center deployments. Alternatively, version 10.2.18 (LTS) is available as a patched release for other environments.

High-Severity DoS Vulnerability via Netty Dependency (CVE-2026-33871)

The second vulnerability, CVE-2026-33871, carries a CVSS score of 8.7, indicating a high-severity risk. This flaw originates from a denial-of-service weakness within the io.netty:netty-codec-http2 library, which is bundled with Bamboo.

Exploitation of this vulnerability could allow an attacker to flood the server with HTTP/2 requests, leading to service disruptions and reduced availability for the continuous integration/continuous delivery (CI/CD) pipelines managed by Bamboo.

Atlassian clarified that while the underlying dependency’s vulnerability might inherently rate higher, their specific implementation of the library reduces the assessed risk to a non-critical level. Nevertheless, applying the recommended patches remains highly important.

Bamboo is a widely adopted CI/CD automation server, integral to enterprise software development workflows. This makes it a prime target for threat actors aiming to compromise development supply chains or inject malicious code into build processes. Command injection vulnerabilities in such environments are particularly dangerous, as they can facilitate tampering with build artifacts or the theft of credentials stored within pipeline configurations.

Fixed versions of Bamboo are now accessible via Atlassian’s official download archives. Administrators must audit their existing Bamboo installations against the identified vulnerable versions and prioritize upgrading to the recommended LTS releases without delay.

What You Should Do

• Immediately identify all Bamboo Data Center and Server instances within your environment.
• Check your current Bamboo versions against the list of affected versions for both CVE-2026-21571 and CVE-2026-33871.
• Prioritize upgrading to the recommended patched versions: 12.1.6 (LTS) for Data Center, or 10.2.18 (LTS) as an alternative.
• As a temporary mitigation while patches are being applied, implement network-level restrictions on access to Bamboo’s administrative interfaces to limit potential exposure.

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