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CVE-2026-18355

389-ds-base: 389-ds-base: heap buffer overflow via sasl wrapped-record length lower-bound underflow in sasl_io_start_packet()

No known exploitation. EPSS puts it in the 57th percentile. Fixed versions are out.

CVSS 3.17.5HighEPSS percentile57th0.8% chance in 30 daysCISA KEVNot listedNo confirmed exploitation
No public exploit knownFix5 products5 fixed builds listed below

Published Updated Sources: CVE.org, NVD

NVD CVE.org

What to do

Find your product and version, then upgrade to the build on the right.

  • Red Hat Directory Server 11.5 E4S for RHEL 8Fixed builds8060020260908152739.0ca98e7eStated by: CVE record
  • Red Hat Directory Server 11.7 E4S for RHEL 8Fixed builds8080020260903102346.f969626eStated by: CVE record
  • Red Hat Directory Server 11.9 for RHEL 8Fixed builds8100020260904171440.37ed7c03Stated by: CVE record
  • Red Hat Directory Server 12.2 E4S for RHEL 9Fixed builds9020020260903155914.1674d574Stated by: CVE record
  • Red Hat Directory Server 12.4 E4S for RHEL 9Fixed builds9040020260903102623.1674d574Stated by: CVE record

Versions as the sources state them. 13 more products have version data. Full version matrix after sign-in

Check it yourselfA free OpenVAS check exists for this CVE. Run it against your hosts.Is your organisation exposed?Request an assessment to establish which checks fit your systems.

What it is

From the CVE record

A heap buffer overflow flaw was found in the SASL I/O layer of 389 Directory Server (389-ds-base). In sasl_io_start_packet(), the wrapped-record length read from the wire is validated only against an upper bound. A small wire length (0, 1, or 2) produces an encrypted_buffer_count below the already-consumed encrypted_buffer_offset, causing an unsigned subtraction underflow in sasl_io_read_packet(). PR_Recv is then requested to read approximately 4 GiB into a 1024-byte heap buffer, resulting in a heap buffer overflow with attacker-controlled content. After a successful SASL bind with integrity protection (SSF > 0), a remote authenticated attacker can cause a denial of service or potentially achieve remote code execution. This flaw is distinct from CVE-2026-11774, whose fix only guards against upper-bound overflow.

In plain language

No plain-language summary for this CVE yet.

Exploitation

Where each signal puts this CVE on the scale from published to confirmed exploited.

EPSS57th
CISA KEV

Not in the catalog. CISA has not confirmed exploitation.

Public exploits

No public exploit or proof of concept found in the sources we track.

EPSS

0.8% chance of exploitation activity in the next 30 days, which ranks it in the 57th percentile of scored CVEs.

Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.

Lifecycle

18 events over 31 days, from the signal feeds we watch.

  1. Workaround availablerecord updated
  2. OpenVAS check added
  3. Workaround availableworkaround available, workaround available, workaround available, workaround available, record updated, record updated, record updated, record updated, record updated
  4. Workaround availablepublished, weakness classified, att&ck mapped, record updated

Affected products

And 15 more affected products. See all after sign-in

Technical detail

CVSS 3.1 vector

Open in the CVSS calculator

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

Scored 7.5 by NVD.

How it is reached

  • Attack Vector NetworkExploitable remotely over the network without any special conditions
  • Attack Complexity HighRequires specific conditions like a race condition or non-default configuration
  • Privileges Required LowRequires basic user-level privileges
  • User Interaction NoneNo user interaction needed — fully automated exploitation

Scope

  • Scope UnchangedImpact is limited to the vulnerable component itself

Impact if exploited

  • Confidentiality HighTotal information disclosure — all data in the component is compromised
  • Integrity HighTotal loss of integrity — attacker can modify any data in the component
  • Availability HighTotal denial of service — the component is completely unavailable

Weaknesses

ATT&CK techniques

Mapped from the weaknesses above (CWE to ATT&CK), not observed in attacks.

Sources

References in the record

And 16 more references. See all after sign-in

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