NULL pointer dereference in OpenSMTPD - CVE-2020-35680
Published: December 24, 2020 / Updated: December 29, 2020
Vulnerability identifier: #VU49179
CSH Severity: Medium
CVSS v4: 8.2 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2020-35680
CWE-ID: CWE-476
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.
The vulnerability exists due to a NULL pointer dereference error in smtpd/lka_filter.c in certain configurations. A remote attacker can trigger denial of service conditions via a crafted pattern of client activity, because the filter state machine does not properly maintain the I/O channel between the SMTP engine and the filters layer.
Affected software
OpenSMTPD
Arch Linux
Gentoo Linux
Fedora
opensmtpd
Arch Linux
Gentoo Linux
Fedora
opensmtpd
How to mitigate CVE-2020-35680
Install update from vendor's website.
OpenSMTPD - update to 6.8.0p1
opensmtpd - addressed in versions 6.8.0p2-1.el7, 6.8.0p2-1.el8, 6.8.0p2-1.fc32, 6.8.0p2-1.fc33
opensmtpd - addressed in versions 6.8.0p2-1.el7, 6.8.0p2-1.el8, 6.8.0p2-1.fc32, 6.8.0p2-1.fc33