Log in Start free

Vulnerability · Published Oct 7, 2026 · Assigned by redhat

CVE-2026-107161Cyrus-sasl: heap buffer overflow in cyrus-sasl add_to_challenge() allows malicious server to crash or compromise digest-md5 clients

High 7.5

In plain English

A high-severity heap buffer overflow in Red Hat Enterprise Linux 10 from Red Hat. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 32% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.5High
Exploit odds (30 days)0.4%top 68.3% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

A heap-based buffer overflow flaw was found in Cyrus SASL. The add_to_challenge() function in the DIGEST-MD5 plugin computes the size of the buffer needed for a challenge/response field before DIGEST-MD5 quoting is applied, but does not recompute that size when quoting (escaping special characters) makes the value longer. The under-sized buffer is then passed to strcat(), causing a heap-based out-of-bounds write whose size depends on attacker-controlled input. A malicious or on-path DIGEST-MD5 (or HTTP Digest) server can trigger this flaw in a connecting client by supplying a crafted challenge field, such as realm or nonce, most likely resulting in a crash of the client application.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12cyrus-sasl22.1.28+dfsg-10+deb12u1DEBIAN-CVE-2026-107161
Debian:13cyrus-sasl2no fix listedDEBIAN-CVE-2026-107161
Debian:14cyrus-sasl22.1.28+dfsg1-12DEBIAN-CVE-2026-107161
Ubuntu:22.04:LTScyrus-sasl2no fix listedUBUNTU-CVE-2026-107161
Ubuntu:24.04:LTScyrus-sasl2no fix listedUBUNTU-CVE-2026-107161
Ubuntu:26.04:LTScyrus-sasl2no fix listedUBUNTU-CVE-2026-107161
Ubuntu:26.10cyrus-sasl2no fix listedUBUNTU-CVE-2026-107161

Affected products (as reported)

VendorProductVersions
Red Hat Red Hat Enterprise Linux 10 see references
Red Hat Red Hat Enterprise Linux 6 see references
Red Hat Red Hat Enterprise Linux 7 see references
Red Hat Red Hat Enterprise Linux 8 see references
Red Hat Red Hat Enterprise Linux 9 see references
Red Hat Red Hat Hardened Images see references
Red Hat Red Hat OpenShift Container Platform 4 see references
Red Hat Red Hat OpenShift Container Platform 4 see references
Red Hat Red Hat OpenShift Container Platform 5 see references

Weakness: CWE-122 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

References