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critical · CVSS 9

CVE-2026-86345

389-ds-base: 389-ds-base: starttls plaintext-buffer retention allows on-path attacker to forge an ldap client's authentication result

Published 1 Oct 2026 · Source updated 6 Nov 2026 · Retrieved 2026-11-06 01:53 UTC

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What happened?

A flaw was found in 389-ds-base. The server does not discard plaintext bytes already buffered from a client connection when negotiating StartTLS, allowing an on-path attacker to inject a crafted LDAP message that is processed after the TLS upgrade and whose response is delivered to the client in place of the client's own pending operation's response, due to messageID collision. This can cause a client application to treat a failed authentication (bind) attempt as successful.

Description supplied by CVE Program. Formatting is simplified; follow the original advisory for full details.

Affected software and versions

Source-provided software and version information
SoftwareVersion informationFixed version
389-ds-baseRed HatDefault status: affectedSee vendor advisory
redhat-ds:11/389-ds-baseRed HatDefault status: affectedSee vendor advisory
389-ds-baseRed HatDefault status: affectedSee vendor advisory
redhat-ds:12/389-ds-baseRed HatDefault status: affectedSee vendor advisory
389-ds-baseRed HatDefault status: affectedSee vendor advisory
389-ds-baseRed HatDefault status: affectedSee vendor advisory
389-ds-baseRed HatDefault status: unknownSee vendor advisory
389-ds-baseRed HatDefault status: unknownSee vendor advisory
389-ds:1.4/389-ds-baseRed HatDefault status: affectedSee vendor advisory
389-ds-baseRed HatDefault status: affectedSee vendor advisory
389-ds-baseRed HatDefault status: affectedSee vendor advisory

Version information comes from the source record and can include unaffected products and exceptions. Distribution packages may contain backported fixes: an older upstream version alone does not prove a server is affected.

Is it being exploited?

This CVE was not listed in the CISA catalogue at our last retrieval. This does not establish that exploitation is absent.

CISA data retrieved 2026-11-06 16:38 UTC. Check CISA ↗

How to respond

  1. Confirm the product, installed package version, and any configuration requirements in the vendor advisory.
  2. Follow the vendor’s remediation or workaround guidance in the references below. Structured fixed-version data is unavailable here; the publisher’s description may include a fix or workaround.
  3. Restart affected services if required, then verify the running version. Known exploitation may warrant investigation as well as patching.

Sources and remediation references

This public advisory does not determine whether a particular server is affected. Records are refreshed as sources change; verify urgent decisions against the original advisory.

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