CVE-2013-6420

CVE-2013-6420 is a high-severity vulnerability in Php with a CVSS 2.0 base score of 7.5. Its EPSS exploit-prediction score of 36% places it in the 98th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-119.

Key facts

Description

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.

Frequently asked questions

What is CVE-2013-6420?
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.
How severe is CVE-2013-6420?
CVE-2013-6420 has a CVSS 2.0 base score of 7.5, rated high severity.
Is CVE-2013-6420 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 36% (98th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2013-6420?
CVE-2013-6420 primarily affects Php. In total, 81 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2013-6420?
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-2013-6420 published?
CVE-2013-6420 was published on 2013-12-17 and last updated on 2026-06-17.

References

Affected products (81)

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Threat intelligence

Threat-intel indicators referencing this CVE: