CVE-2022-37451 — Exim before 4

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.

01What is this vulnerability?

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.

02Affected products

Vendor	Product	Versions
n	a / n/a	n/a

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: 2022-08-06T17:02:11.000Z
• Last modified: 2024-08-03T10:29:21.028Z

09References

• github.com — https://github.com/Exim/exim/wiki/EximSecurity
• www.exim.org — https://www.exim.org/static/doc/security/
• github.com — https://github.com/ivd38/exim_invalid_free
• www.openwall.com — https://www.openwall.com/lists/oss-security/2022/08/06/1
• lists.exim.org — https://lists.exim.org/lurker/message/20220625.141825.d6de6074.en.html
• cwe.mitre.org — https://cwe.mitre.org/data/definitions/762.html
• github.com — https://github.com/Exim/exim/compare/exim-4.95...exim-4.96
• github.com — https://github.com/Exim/exim/commit/51be321b27825c01829dffd90f11bfff256f7e42
• 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…