CVE-2026-77711 Eclipse Foundation CVE debrief

Who should care

Defenders responsible for Jetty deployments using HttpClient through forward proxies should assess exposure and verify affected versions. Security teams and vulnerability management teams should prioritize verification of affected versions and configurations. Operators and administrators of affected systems should monitor for potential exploitation attempts and review compensating controls. IT and security teams should work together to assess the impact on

Why it matters

CVE-2026-77711 is a high-severity vulnerability in Jetty's HttpClient that can lead to potential credential exposure. Defenders responsible for Jetty deployments using HttpClient through forward proxies should assess exposure and verify affected versions.

• Potential credential exposure due to incorrect interpretation of 407 responses
• Verification of affected versions and configurations is required
• Monitoring for potential exploitation attempts is necessary

Technical summary

The Jetty HttpClient incorrectly interprets a 407 Proxy Authentication Required response from a server through a forward proxy. This leads to potential credential exposure as the client re-sends the request with the Proxy-Authentication header. The vulnerability has a CVSS score of 8.2 and is considered HIGH severity. Affected deployments using HttpClient through forward proxies should be assessed for exposure. Verification of affected versions and configurations is required, and monitoring for potential exploitation attempts is necessary.

Defensive priority

Defenders should prioritize verification of affected versions and configurations, and assess exposure in their environments.

Recommended defensive actions

• Verify affected versions and configurations
• Assess exposure in environments
• Monitor for potential exploitation attempts
• Review compensating controls for exposed systems
• Check relevant monitoring, detection, and logs for exposed assets
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and NVD entry provide limited information about the vulnerability. Further investigation is required to determine the affected versions and configurations. The vulnerability has a high severity score of 8.2 and is classified as HIGH. The CVE record was published on 2026-10-15T09:17:18.573Z and has not been modified since then. The NVD entry and CVE Program record offer additional details on the vulnerability.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.