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PatchSiren cyber security CVE debrief

CVE-2026-40516 HKUDS CVE debrief

CVE-2026-40516 is a high-severity vulnerability in OpenHarness, a tool for continuous integration and delivery. The vulnerability allows attackers to access private and localhost HTTP services by manipulating tool parameters without proper validation of target addresses. This can be done by influencing an agent session to invoke the web_fetch and web_search tools against loopback, RFC1918, link-local, or other non-public addresses to read response bodies from local development services, cloud metadata endpoints, admin panels, or other private HTTP services reachable from the victim host. Users of OpenHarness, particularly those who use the web_fetch and web_search tools, should take immediate action to mitigate this vulnerability.

Vendor
HKUDS
Product
OpenHarness
CVSS
HIGH 7.8
CISA KEV
Not listed in stored evidence
Original CVE published
2026-04-17
Original CVE updated
2026-07-14
Advisory published
2026-04-17
Advisory updated
2026-07-14

Who should care

This vulnerability affects users of OpenHarness, particularly those who use the web_fetch and web_search tools. It is recommended that users take immediate action to mitigate this vulnerability by applying the patch provided by the vendor and restricting access to the affected tools.

Technical summary

The vulnerability is caused by a lack of proper validation of target addresses in the web_fetch and web_search tools of OpenHarness. This allows attackers to manipulate tool parameters and access private and localhost HTTP services. The vulnerability has a high CVSS score of 7.8, indicating a high level of severity. Affected product deployments should be identified and owners assigned for follow-up. Official advisories and CVE records should be reviewed to validate affected scope, severity, and vendor guidance.

Defensive priority

High

Recommended defensive actions

  • Apply the patch provided by the vendor
  • Restrict access to the web_fetch and web_search tools
  • Monitor for suspicious activity
  • Implement additional security measures to protect against SSRF attacks
  • Review compensating controls for exposed systems while remediation is scheduled and verified
  • Check relevant monitoring, detection, and logs for exposed assets that need extra review
  • Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The vulnerability was reported by an unknown researcher and was patched by the vendor. The patch is available on GitHub. Further verification is recommended to confirm affected scope and severity. Evidence limits suggest that additional information may be available but has not been disclosed. Defenders should verify the patch and review system logs for potential exploitation.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-40516 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-40516

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-40516 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-40516

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental 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.