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 56th percentile. Only a workaround so far.
What to do
No fixed build is published yet. The vendor describes a workaround.
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.
- 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 56th percentile of scored CVEs.
Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.
Lifecycle
16 events over 2 days, from the signal feeds we watch.
- OpenVAS check added
- Workaround availableworkaround available, workaround available, workaround available, workaround available, record updated, record updated, record updated, record updated, record updated
- Workaround availablepublished, weakness classified, att&ck mapped, record updated
Affected products
- Red Hat Directory Server 11.7 E4S for RHEL 8Enterprise Software / itsm-monitoring
- Red Hat Directory Server 11.9 for RHEL 8Databases / db-tooling
- Red Hat Directory Server 12.2 E4S for RHEL 9Enterprise Software / itsm-monitoring
- Red Hat Directory Server 12.4 E4S for RHEL 9Databases / relational
- Red Hat Enterprise Linux 10Operating Systems / linux-distro
- Red Hat Enterprise Linux 10.0 Extended Update SupportOperating Systems / linux-distro
- Red Hat Enterprise Linux 7 Extended Lifecycle SupportOperating Systems / linux-distro
- Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update SupportOperating Systems / linux-distro
And 14 more affected products. See all after sign-in
Technical detail
CVSS 3.1 vector
Open in the CVSS calculatorCVSS: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.
- Initial AccessT1190Exploit Public-Facing Applicationmedium confidence
Sources
References in the record
- access.redhat.com/errata/RHSA-2026:64771
- access.redhat.com/errata/RHSA-2026:64776
- access.redhat.com/errata/RHSA-2026:64778
And 15 more references. See all after sign-in
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