CVE-2022-4450
Double free after calling PEM_read_bio_ex
Severity Score
Exploit Likelihood
Affected Versions
Public Exploits
0Exploited in Wild
-Decision
Descriptions
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.
A double-free vulnerability was found in OpenSSL's PEM_read_bio_ex function. The function PEM_read_bio_ex() reads a PEM file from a BIO and parses and decodes the "name" (for example, "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. Constructing a PEM file that results in 0 bytes of payload data is possible. In this case, PEM_read_bio_ex() will return a failure code but will populate the header argument with a pointer to a freed buffer. A double-free will occur if the caller also frees this buffer. This will most likely lead to a crash. This could be exploited by an attacker who can supply malicious PEM files for parsing to achieve a denial of service attack.
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.
There is a type confusion vulnerability relating to X.400 address processing inside an X.509 GeneralName. X.400 addresses were parsed as an ASN1_STRING but the public structure definition for GENERAL_NAME incorrectly specified the type of the x400Address field as ASN1_TYPE. This field is subsequently interpreted by the OpenSSL function GENERAL_NAME_cmp as an ASN1_TYPE rather than an ASN1_STRING. A timing based side channel exists in the OpenSSL RSA Decryption implementation. The public API function BIO_new_NDEF is a helper function used for streaming ASN.1 data via a BIO. It is primarily used internally to OpenSSL to support the SMIME, CMS and PKCS7 streaming capabilities, but may also be called directly by end user applications. The function receives a BIO from the caller, prepends a new BIO_f_asn1 filter BIO onto the front of it to form a BIO chain, and then returns the new head of the BIO chain to the caller. Under certain conditions, for example if a CMS recipient public key is invalid, the new filter BIO is freed and the function returns a NULL result indicating a failure. However, in this case, the BIO chain is not properly cleaned up and the BIO passed by the caller still retains internal pointers to the previously freed filter BIO. 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. When CRL checking is enabled (i.e. the application sets the X509_V_FLAG_CRL_CHECK flag), this vulnerability may allow an attacker to pass arbitrary pointers to a memcmp call, enabling them to read memory contents or enact a denial of service. In most cases, the attack requires the attacker to provide both the certificate chain and CRL, neither of which need to have a valid signature. If the attacker only controls one of these inputs, the other input must already contain an X.400 address as a CRL distribution point, which is uncommon. As such, this vulnerability is most likely to only affect applications which have implemented their own functionality for retrieving CRLs over a network. A timing based side channel exists in the OpenSSL RSA Decryption implementation which could be sufficient to recover a plaintext across a network in a Bleichenbacher style attack. To achieve a successful decryption an attacker would have to be able to send a very large number of trial messages for decryption. The vulnerability affects all RSA padding modes: PKCS#1 v1.5, RSA-OEAP and RSASVE. A use-after-free will occur under certain conditions. This will most likely result in a crash. A double free may 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.
CVSS Scores
SSVC
- Decision:Attend
Timeline
- 2022-12-13 CVE Reserved
- 2023-02-07 CVE Published
- 2025-05-05 CVE Updated
- 2025-05-16 EPSS Updated
- ---------- Exploited in Wild
- ---------- KEV Due Date
- ---------- First Exploit
CWE
- CWE-415: Double Free
CAPEC
References (6)
URL | Tag | Source |
---|---|---|
https://security.gentoo.org/glsa/202402-08 |
|
URL | Date | SRC |
---|
URL | Date | SRC |
---|---|---|
https://www.openssl.org/news/secadv/20230207.txt | 2024-02-04 | |
https://access.redhat.com/security/cve/CVE-2022-4450 | 2023-06-05 | |
https://bugzilla.redhat.com/show_bug.cgi?id=2164494 | 2023-06-05 |
Affected Vendors, Products, and Versions
Vendor | Product | Version | Other | Status | ||||||
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Vendor | Product | Version | Other | Status | <-- --> | Vendor | Product | Version | Other | Status |
Openssl Search vendor "Openssl" | Openssl Search vendor "Openssl" for product "Openssl" | >= 1.1.1 < 1.1.1t Search vendor "Openssl" for product "Openssl" and version " >= 1.1.1 < 1.1.1t" | - |
Affected
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Openssl Search vendor "Openssl" | Openssl Search vendor "Openssl" for product "Openssl" | >= 3.0.0 < 3.0.8 Search vendor "Openssl" for product "Openssl" and version " >= 3.0.0 < 3.0.8" | - |
Affected
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Stormshield Search vendor "Stormshield" | Stormshield Network Security Search vendor "Stormshield" for product "Stormshield Network Security" | >= 4.0.0 < 4.3.16 Search vendor "Stormshield" for product "Stormshield Network Security" and version " >= 4.0.0 < 4.3.16" | - |
Affected
| ||||||
Stormshield Search vendor "Stormshield" | Stormshield Network Security Search vendor "Stormshield" for product "Stormshield Network Security" | >= 4.4.0 < 4.6.3 Search vendor "Stormshield" for product "Stormshield Network Security" and version " >= 4.4.0 < 4.6.3" | - |
Affected
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