CVE-2026-86345 Red Hat CVE debrief

Who should care

Defenders responsible for LDAP authentication configurations, particularly those using 389-ds-base, should assess exposure and prioritize patching. This includes system administrators, security teams, and IT professionals managing LDAP authentication. They should review and update configurations, monitor for suspicious activity, and verify patch application to mitigate potential impacts on client applications and authentication processes.

Why it matters

Defenders should care about CVE-2026-86345 because it allows an on-path attacker to potentially forge LDAP authentication results, impacting client applications and requiring prompt patching and monitoring.

• Potential for authentication result forgery
• Possible impact on client application authentication
• Need for verification of patch application
• Importance of monitoring LDAP activity

Technical summary

The 389-ds-base server does not discard plaintext bytes from a client connection when negotiating StartTLS, allowing an on-path attacker to inject a crafted LDAP message. This can cause a client application to treat a failed authentication (bind) attempt as successful due to messageID collision. The vulnerability impacts client applications and requires prompt patching and monitoring to mitigate potential authentication result forgery. Affected systems should prioritize verifying and applying patches for 389-ds-base.

Defensive priority

Defenders should prioritize verifying and applying patches for 389-ds-base, especially for systems handling LDAP authentication.

Recommended defensive actions

• Verify and apply patches for 389-ds-base
• Review and update LDAP authentication configurations
• Monitor for suspicious LDAP activity
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up
• 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 CVE record and source item provide details on the flaw in 389-ds-base, including its impact on LDAP authentication. Evidence is limited to public CVE details and may not reflect all affected systems or specific vendor mitigations. Defenders should verify patch application and monitor for suspicious LDAP activity. The flaw was reported in 389-ds-base and impacts systems using LDAP authentication.

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.