CVE-2026-57303
HIGHJenkins Assembla Plugin 1.4 and earlier does not configure its XML parser to prevent XML external entity (XXE) attacks, allowing attackers able to control the responses of the configured…
Description
Jenkins Assembla Plugin 1.4 and earlier does not configure its XML parser to prevent XML external entity (XXE) attacks, allowing attackers able to control the responses of the configured Assembla server to extract secrets from the Jenkins controller or perform server-side request forgery.
Affected Products
assemblajenkinsDetection & mitigation playbook
Vendor / applianceDetect
Inventory every jenkins assembla deployment and check each version against the affected-products list above. Because the exploit targets the running system rather than your application code, also watch for exploitation at the network and runtime layer — O3 flags the exploit behaviour from runtime telemetry and egress traffic even before a vulnerable build is confirmed.
Remediation status
No patch has shipped for CVE-2026-57303 yet — track the jenkins assembla advisory for a fixed release and apply the workarounds below in the meantime.
Mitigate without a patch
Cut exposure now: restrict the management/admin interface to trusted networks, segment the device, and apply the vendor's recommended configuration mitigations and any WAF/IPS signature. O3's runtime protection blocks the exploit chain at execution, holding the line on unpatched or end-of-life systems until you can patch.
How O3 protects you
O3 detects and blocks CVE-2026-57303 exploitation at runtime: eBPF exploit-chain detection, plus L7 egress monitoring that catches the post-exploitation callback and severs the attacker's outbound channel.
Tailored to CVE-2026-57303. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-57303 being exploited in your environment?
O3's eBPF runtime sensors and L7 egress monitoring detect and block the CVE-2026-57303 exploit chain at execution — protecting unpatched and end-of-life systems until the vendor patch is applied.