CVE-2019-19906 — cyrus-sasl (aka Cyrus SASL) 2

cyrus-sasl (aka Cyrus SASL) 2.1.27 has an out-of-bounds write leading to unauthenticated remote denial-of-service in OpenLDAP via a malformed LDAP packet. The OpenLDAP crash is ultimately caused by an off-by-one error in _sasl_add_string in common.c in cyrus-sasl.

01What is this vulnerability?

cyrus-sasl (aka Cyrus SASL) 2.1.27 has an out-of-bounds write leading to unauthenticated remote denial-of-service in OpenLDAP via a malformed LDAP packet. The OpenLDAP crash is ultimately caused by an off-by-one error in _sasl_add_string in common.c in cyrus-sasl.

02Affected products

No structured affected-product list available — see references below for vendor advisories.

03Active exploitation status

Not currently listed on the CISA Known Exploited Vulnerabilities (KEV) catalog. EPSS is the best forward-looking signal — see the EPSS row above.

04Recommended remediation

• Patch to a fixed version listed in the vendor advisory (see references below).
• Mitigate with WAF rules, network egress filters, or feature flags where the patch is not yet available.
• Hunt historical logs for exploitation indicators — see Detection signatures below.

05Technical details

For the full vendor write-up, exploit chains, and reference implementations, see the references list in section 09.

06Detection signatures

Ask SARA in chat to draft a starting detection for this CVE in your stack of choice.

07Related CVEs

No directly-cited follow-up CVEs in the KB record for this advisory. The references list in section 09 carries the vendor cross-references.

08Timeline

• Published: 2019-12-19T18:15:12.833
• Last modified: 2026-10-14T08:16:59.200

09References

• seclists.org — http://seclists.org/fulldisclosure/2020/Jul/23
• seclists.org — http://seclists.org/fulldisclosure/2020/Jul/24
• www.openwall.com — http://www.openwall.com/lists/oss-security/2022/02/23/4
• github.com — https://github.com/cyrusimap/cyrus-sasl/issues/587
• lists.apache.org — https://lists.apache.org/thread.html/r58af02e294bd07f487e2c64ffc0a29b837db5600e3…
• lists.apache.org — https://lists.apache.org/thread.html/rf4c02775860db415b4955778a131c2795223f61cb8…
• lists.debian.org — https://lists.debian.org/debian-lts-announce/2019/12/msg00027.html
• lists.fedoraproject.org — https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedorapro…
• lists.fedoraproject.org — https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedorapro…
• seclists.org — https://seclists.org/bugtraq/2019/Dec/42