CVE-2026-18355

7.5 HIGH 0.8% exploit odds No fix listed Code execution Server

What it is

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.

At a glance

Exploitability: Can be exploited over the network with a low-privilege account. High risk of data exposure, data tampering, service disruption.
Exploit odds: 0.8% chance of exploitation in the next 30 days (EPSS).
Fix: No patch or advisory is linked yet. Look at mitigations or restrict exposure.

Timeline

2026-09-07 15:17 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-11-04 22:18 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 0.8% in the next 30 days (EPSS).
Severity: 7.5 HIGH (CVSS).
Fix: none linked yet, which raises it.

Details

Published: 2026-09-07 15:17 UTC
Last modified: 2026-11-04 22:18 UTC
Exploit probability: 0.8% · EPSS, next 30 days
Weakness: CWE-191
Record status: Awaiting Analysis

Attack profile CVSS 3.1 · 7.5

Attack vector: Network
Complexity: High
Privileges needed: Low
User interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
Availability: High

Raw vector

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

Is it in your code?

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References

NVD record · CVE.org record