CVE-2013-6422

Severity: medium (CVSS 4.0 v2.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 2.8% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2013-12-23 · updated 2026-06-17
Weakness: CWE-20

Description

The GnuTLS backend in libcurl 7.21.4 through 7.33.0, when disabling digital signature verification (CURLOPT_SSL_VERIFYPEER), also disables the CURLOPT_SSL_VERIFYHOST check for CN or SAN host name fields, which makes it easier for remote attackers to spoof servers and conduct man-in-the-middle (MITM) attacks.

Affected products

Canonical Ubuntu Linux: 12.04, 12.10, 13.04, 13.10
Debian Linux: 7.0
curl: 7.21.4, 7.21.5, 7.21.6, 7.21.7, 7.22.0, 7.23.0 (+12)

References

http://curl.haxx.se/docs/adv_20131217.html
http://www.debian.org/security/2013/dsa-2824
http://www.oracle.com/technetwork/topics/security/cpujul2015-2367936.html
http://www.ubuntu.com/usn/USN-2058-1
https://h20564.www2.hp.com/hpsc/doc/public/display?docId=emr_na-c04463322
http://curl.haxx.se/docs/adv_20131217.html
http://www.debian.org/security/2013/dsa-2824
http://www.oracle.com/technetwork/topics/security/cpujul2015-2367936.html
http://www.ubuntu.com/usn/USN-2058-1
https://h20564.www2.hp.com/hpsc/doc/public/display?docId=emr_na-c04463322

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