Summary
Package updates are available for Amazon Linux 2 that fix the following vulnerabilities: CVE-2026-107161: 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.
Fixed packages 12
| Release | Package | Fixed in |
|---|---|---|
| Amazon Linux · 2 | cyrus-sasl | 0:2.1.26-24.amzn2.0.2 |
| Amazon Linux · 2 | cyrus-sasl-debuginfo | 0:2.1.26-24.amzn2.0.2 |
| Amazon Linux · 2 | cyrus-sasl-devel | 0:2.1.26-24.amzn2.0.2 |
| Amazon Linux · 2 | cyrus-sasl-gs2 | 0:2.1.26-24.amzn2.0.2 |
| Amazon Linux · 2 | cyrus-sasl-gssapi | 0:2.1.26-24.amzn2.0.2 |
| Amazon Linux · 2 | cyrus-sasl-ldap | 0:2.1.26-24.amzn2.0.2 |
| Amazon Linux · 2 | cyrus-sasl-lib | 0:2.1.26-24.amzn2.0.2 |
| Amazon Linux · 2 | cyrus-sasl-md5 | 0:2.1.26-24.amzn2.0.2 |
| Amazon Linux · 2 | cyrus-sasl-ntlm | 0:2.1.26-24.amzn2.0.2 |
| Amazon Linux · 2 | cyrus-sasl-plain | 0:2.1.26-24.amzn2.0.2 |
| Amazon Linux · 2 | cyrus-sasl-scram | 0:2.1.26-24.amzn2.0.2 |
| Amazon Linux · 2 | cyrus-sasl-sql | 0:2.1.26-24.amzn2.0.2 |
Vulnerabilities 1
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High 7.5
Cyrus-sasl: heap buffer overflow in cyrus-sasl add_to_challenge() allows malicious server to crash or compromise digest-md5 clients
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 wh…
References
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web
https://alas.aws.amazon.com/cve/html/CVE-2026-107161.html