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CVE-2013-6420

HIGH severity · CVSS 7.5 · Memory corruption
7.5CVSS HIGH

Summary

The asn1_time_to_time_t function in ext/openssl/openssl.c in PHP before 5.3.28, 5.4.x before 5.4.23, and 5.5.x before 5.5.7 does not properly parse (1) notBefore and (2) notAfter timestamps in X.509 certificates, which allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via a crafted certificate that is not properly handled by the openssl_x509_parse function.

Impact & exploitability

Attack vectorNetwork
Attack complexityLow
Privileges required
User interaction
Confidentiality impact
Integrity impact
Availability impact
Exploit probability (EPSS)40%

AV:N/AC:L/Au:N/C:P/I:P/A:P

Affected products we track (1)

PHP

Recommendation

Apply the vendor fix promptly. Open any affected product above for its exact safe version.

Last checked: Wed, 10 Jun 2026 22:18:30 UTC