CVE-2009-4565

CVE-2009-4565 is a high-severity vulnerability in Sendmail with a CVSS 2.0 base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-310.

Key facts

Description

sendmail before 8.14.4 does not properly handle a '\0' character in a Common Name (CN) field of an X.509 certificate, which (1) allows man-in-the-middle attackers to spoof arbitrary SSL-based SMTP servers via a crafted server certificate issued by a legitimate Certification Authority, and (2) allows remote attackers to bypass intended access restrictions via a crafted client certificate issued by a legitimate Certification Authority, a related issue to CVE-2009-2408.

Frequently asked questions

What is CVE-2009-4565?
sendmail before 8.14.4 does not properly handle a '\0' character in a Common Name (CN) field of an X.509 certificate, which (1) allows man-in-the-middle attackers to spoof arbitrary SSL-based SMTP servers via a crafted server certificate issued by a legitimate Certification Authority, and (2) allows remote attackers to bypass intended access restrictions via a crafted client certificate issued by a legitimate Certification Authority, a related issue to CVE-2009-2408.
How severe is CVE-2009-4565?
CVE-2009-4565 has a CVSS 2.0 base score of 7.5, rated high severity.
Is CVE-2009-4565 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (82nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2009-4565?
CVE-2009-4565 primarily affects Sendmail. In total, 62 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2009-4565?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2009-4565 published?
CVE-2009-4565 was published on 2010-01-04 and last updated on 2026-06-16.

References

Affected products (62)

More vulnerabilities in Sendmail

All CVEs affecting Sendmail →

Other CWE-310 (Cryptographic Issues) vulnerabilities

Browse all CWE-310 (Cryptographic Issues) vulnerabilities →