CVE-2022-4450 Double free after calling PEM_read_bio_ex

What is CVE-2022-4450?

CVE-2022-4450 is a high-severity use after free vulnerability in Openssl Openssl, published on 8 Feb 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official 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.

Weakness: CWE-415

Which versions are affected by CVE-2022-4450?

5 open source packages ship an affected version, including openssl-src. It affects 2 products.

Products include Openssl Openssl, Stormshield Stormshield Network Security.

How do I fix CVE-2022-4450?

Upgrade openssl-src to a fixed version for your release line: 111.25.0 or 300.0.12.

Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.

Is CVE-2022-4450 being exploited?

There is no known exploitation of CVE-2022-4450 in the wild and no public exploit code.

Other vulnerabilities in Openssl Openssl

• CVE-2009-3245 Null dereference in n/a Critical 10.0
• CVE-2006-3738 Memory corruption in n/a Critical 10.0
• CVE-2026-63073 Untrusted Sender DN Used as Format String in CMP Response Validation Critical 9.8
• CVE-2016-6309 Use after free in n/a Critical 9.8
• CVE-2016-0799 Integer overflow in n/a Critical 9.8

All Openssl Openssl vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as ALPINE-CVE-2022-4450, AZL-13347, AZL-13351, AZL-37629, AZL-37892, CLEANSTART-2026-LY01438 and 7 more.