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PSF-2019-13

Published Jul 1, 2019·Last modified Oct 9, 2025
Affected Components(0)

No affected components available

Description

inet_aton() accepts trailing characters after a valid IP. Because of that, Python ssl.match_hostname('1.1.1.1 ; this should not work but does') succeeded when it should fail.

The issue was introduced in bpo-32819 <https://bugs.python.org/issue32819>_ by commit aef1283b <https://github.com/python/cpython/commit/aef1283ba428e33397d87cee3c54a5110861552d>_. Only Python 3.7 and newer are affected. It's a potential security bug although low severity. For one Python 3.7 and newer no longer use ssl.match_hostname() to verify hostnames and IP addresses of a certificate: matching is performed by OpenSSL.

It should not possible to register a x509 certificate with a hostname with spaces.

The glibc function inet_aton() accepts input as valid if said input is a IPv4 address followed by zero or more characters that are valid white-space as decided by isspace(), with the rest of the string after the first white-space being ignored. As '\r' is a valid white-space character the rest of the string is ignored (including the '\r'). See glibc bug 24111: Deprecate inet_addr, inet_aton <https://sourceware.org/bugzilla/show_bug.cgi?id=24111>_.

Risk Scores
Base Score
0.0

Measures severity based on intrinsic characteristics of the vulnerability, independent of environment.

Threat Intelligence
0.0

No exploitation activity has been observed at this time. Continue routine monitoring.

EPSS
N/A

Probability that this vulnerability will be exploited in the wild within the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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