CVE-2022-4450: The function PEM_read_bio_ex() reads a PEM file from a BIO and parses and decodes the "name" (e.g. "CERTIFICATE"), any header data and the payload dat...

Description

The function PEM_read_bio_ex() reads a PEM file from a BIO and parses and decodes the "name" (e.g. "CERTIFICATE"), any header data and the payload data. If the function succeeds then the "name_out", "header" and "data" arguments are populated with pointers to buffers containing the relevant decoded data. The caller is responsible for freeing those buffers. It is possible to construct a PEM file that results in 0 bytes of payload data. In this case PEM_read_bio_ex() will return a failure code but will populate the header argument with a pointer to a buffer that has already been freed. If the caller also frees this buffer then a double free will occur. This will most likely lead to a crash. This could be exploited by an attacker who has the ability to supply malicious PEM files for parsing to achieve a denial of service attack. The functions PEM_read_bio() and PEM_read() are simple wrappers around PEM_read_bio_ex() and therefore these functions are also directly affected. These functions are also called indirectly by a number of other OpenSSL functions including PEM_X509_INFO_read_bio_ex() and SSL_CTX_use_serverinfo_file() which are also vulnerable. Some OpenSSL internal uses of these functions are not vulnerable because the caller does not free the header argument if PEM_read_bio_ex() returns a failure code. These locations include the PEM_read_bio_TYPE() functions as well as the decoders introduced in OpenSSL 3.0. The OpenSSL asn1parse command line application is also impacted by this issue.

Metrics

CVSS 3.1

7.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS Probability

20.44%

97.2th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Openssl	Openssl	>= 1.1.1, < 1.1.1t
Openssl	Openssl	>= 3.0.0, < 3.0.8
Stormshield	Stormshield Network Security	>= 4.0.0, < 4.3.16
Stormshield	Stormshield Network Security	>= 4.4.0, < 4.6.3

References

https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=63bcf189be73a9cc1264059bed6f57974be74a83Patch, Vendor Advisory
https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=bbcf509bd046b34cca19c766bbddc31683d0858bPatch, Vendor Advisory
https://security.gentoo.org/glsa/202402-08
https://www.openssl.org/news/secadv/20230207.txtVendor Advisory
https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=63bcf189be73a9cc1264059bed6f57974be74a83Patch, Vendor Advisory
https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=bbcf509bd046b34cca19c766bbddc31683d0858bPatch, Vendor Advisory
https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2023-0003
https://security.gentoo.org/glsa/202402-08
https://www.openssl.org/news/secadv/20230207.txtVendor Advisory

Timeline

Published: Feb 8, 2023
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2022-4450?

The function PEM_read_bio_ex() reads a PEM file from a BIO and parses and decodes the "name" (e.g. "CERTIFICATE"), any header data and the payload data. If the function succeeds then the "name_out", "header" and "data" arguments are populated with pointers to buffers containing the relevant decoded data. The caller is responsible for freeing those buffers. It is possible to construct a PEM file that results in 0 bytes of payload data. In this case PEM_read_bio_ex() will return a failure code but will populate the header argument with a pointer to a buffer that has already been freed. If the caller also frees this buffer then a double free will occur. This will most likely lead to a crash. This could be exploited by an attacker who has the ability to supply malicious PEM files for parsing to achieve a denial of service attack. The functions PEM_read_bio() and PEM_read() are simple wrappers around PEM_read_bio_ex() and therefore these functions are also directly affected. These functions are also called indirectly by a number of other OpenSSL functions including PEM_X509_INFO_read_bio_ex() and SSL_CTX_use_serverinfo_file() which are also vulnerable. Some OpenSSL internal uses of these functions are not vulnerable because the caller does not free the header argument if PEM_read_bio_ex() returns a failure code. These locations include the PEM_read_bio_TYPE() functions as well as the decoders introduced in OpenSSL 3.0. The OpenSSL asn1parse command line application is also impacted by this issue.

How severe is CVE-2022-4450?

CVE-2022-4450 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 20.44% probability of exploitation in the next 30 days.

How do I fix CVE-2022-4450?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.