High 7.5

A heap buffer overflow flaw was found in the SASL I/O layer of 389 Directory Server (389-ds-base)...

CVE-2026-18355 First seen on SecPulse Sep 8, 00:17

Summary

Vulnerability reported (CVE-2026-18355). Successful exploitation can lead to full system takeover.

AI summary

Produced by SecPulse using an external AI model; it may contain mistakes. Check the original description and references below before acting on it.

A vulnerability tracked as CVE-2026-18355 has been found.
Successful exploitation can lead to full system takeover. CVSS score: 7.5/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "CVE-2026-18355" on the vendor's site.

CVE-2026-18355 — CWE-191 / CVSS v3 7.5
Attack vector: remote (network-reachable) / no user interaction
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

What is the problem

A vulnerability (CWE-191) has been reported.

Affected scope

Check the vendor advisory for the affected versions.

Severity

Severity: High (CVSS 7.5/10). Successful exploitation can lead to full system takeover.

How to fix

Update to the patched release per vendor advisory.

Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

1
Identify exposureidentify
```
Audit SBOM/dependencies for affected components.
```
資産台帳・SBOM・依存マニフェストで影響コンポーネントを特定する。
2
Post-deployment verificationverify
```
Confirm patched version is live in production
```
パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Fix status by distribution

Records published by each distribution for this CVE. Fixed versions differ by release; check each link.

Debian DEBIAN-CVE-2026-18355 389-ds-base No fixed version in this record
Ubuntu UBUNTU-CVE-2026-18355 389-ds-base No fixed version in this record

Original description The description as published by the source.

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.

Source: NIST National Vulnerability Database NVD GitHub Advisory

Summary

AI summary

Response actions

Fix status by distribution

References