inftrees.c in zlib 1.2.8 might allow context-dependent attackers to have unspecified impact by leveraging improper pointer arithmetic

Last updated 11 July 2025

An old inffast.c optimization turns out to not be optimal anymore with modern compilers, and furthermore was not compliant with the C standard, for which decrementing a pointer before its allocated memory is undefined.

External References:

https://wiki.mozilla.org/images/0/09/Zlib-report.pdf https://docs.google.com/document/d/10i1KZS5so8xDqH2rplRa2xet0tyTvvJlLbQQmZIUIKE/edit#heading=h.t13tvnx4loq7

Upstream patch:

https://github.com/madler/zlib/commit/9aaec95e82117c1cb0f9624264c3618fc380cecb

CVE assignment:

http://seclists.org/oss-sec/2016/q4/602

Last updated 14 January 2026

Last updated 24 July 2024

If an SSL/TLS server or client is running on a 32-bit host, and a specific cipher is being used, then a truncated packet can cause that server or client to perform an out-of-bounds read, usually resulting in a crash.

For Openssl 1.0.2, the crash can be triggered when using RC4-MD5; users who have not disabled that algorithm should update to 1.0.2k

External References:

https://www.openssl.org/news/secadv/20170126.txt

Last updated 24 July 2024