CVE-2022-37451

Exim before 4.96 has an invalid free in pam_converse in auths/call_pam.c because store_free is not used after store_malloc.

Weakness

The product attempts to return a memory resource to the system, but it calls the wrong release function or calls the appropriate release function incorrectly.

Affected Software

Extended Description

This weakness can take several forms, such as:

Potential Mitigations

• Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
• For example, glibc in Linux provides protection against free of invalid pointers.

References

• https://cwe.mitre.org/data/definitions/762.html
• https://github.com/Exim/exim/commit/51be321b27825c01829dffd90f11bfff256f7e42
• https://github.com/Exim/exim/compare/exim-4.95...exim-4.96
• https://github.com/Exim/exim/wiki/EximSecurity
• https://github.com/ivd38/exim_invalid_free
• https://lists.exim.org/lurker/message/20220625.141825.d6de6074.en.html
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LETR5CVDPFOFQHXCJP6NFLG52JZHQYDY/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/XSWDF4QEXD4TDWQLYQOWCHBJKTDQR4Z7/
• https://www.exim.org/static/doc/security/
• https://www.openwall.com/lists/oss-security/2022/08/06/1