CVE-2026-183557.5HighCWE-191

CVE-2026-18355: 389-ds-base: heap buffer overflow via sasl wrapped-record length lower-bound underflow in sasl_io_start_packet()

Red Hat · Red Hat Directory Server 11.5 E4S for RHEL 8

Vendor fix available · Affected: Red Hat Directory Server 11.5 E4S for RHEL 8 · Exploitation: unlikely (under 1%)

Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.

0.8%probability of exploitation in the next 30 days

58th percentile

050100

Higher than 58% of scored CVEs

7.5HighCVSS 3.1

LowMediumHighCrit.

DescriptionCVE.org

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.

Affected products20

From the CVE record. A product or version that is not listed is unknown, not unaffected.

Red Hat · Red Hat Directory Server 11.5 E4S for RHEL 8Versions not stated
Red Hat · Red Hat Directory Server 11.7 E4S for RHEL 8Versions not stated
Red Hat · Red Hat Directory Server 11.9 for RHEL 8Versions not stated
Red Hat · Red Hat Directory Server 12.2 E4S for RHEL 9Versions not stated
Red Hat · Red Hat Directory Server 12.4 E4S for RHEL 9Versions not stated
Red Hat · Red Hat Enterprise Linux 10Versions not stated
Red Hat · Red Hat Enterprise Linux 10.0 Extended Update SupportVersions not stated
Red Hat · Red Hat Enterprise Linux 7 Extended Lifecycle SupportVersions not stated
Red Hat · Red Hat Enterprise Linux 8Versions not stated
Red Hat · Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update SupportVersions not stated
Red Hat · Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-OnVersions not stated
Red Hat · Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update SupportVersions not stated
Red Hat · Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-OnVersions not stated
Red Hat · Red Hat Enterprise Linux 8.8 Telecommunications Update ServiceVersions not stated
Red Hat · Red Hat Enterprise Linux 8.8 Update Services for SAP SolutionsVersions not stated
Red Hat · Red Hat Enterprise Linux 9Versions not stated
Red Hat · Red Hat Enterprise Linux 9.2 Update Services for SAP SolutionsVersions not stated
Red Hat · Red Hat Enterprise Linux 9.4 Update Services for SAP SolutionsVersions not stated
Red Hat · Red Hat Enterprise Linux 9.6 Extended Update SupportVersions not stated
Red Hat · Red Hat Directory Server 13.2Versions not stated

On the Atlas

Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.

Open the Atlas

Exploitation: Unlikely (under 1%). EPSS under 1%, or no score yet.
CISA KEV: Not listed
Public check: No public nuclei template
Weakness: Integer Underflow (Wrap or Wraparound) · Memory Corruption
Vendor: Red Hat
Published: September 2026
Band: Unlikely (under 1%), September 2026

CoverageNo articles yet

No CyberSIXT article names CVE-2026-18355 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.

References

7 more references are in the CVE record.