CVE-2022-4450 | Date: (C)2023-02-09 (M)2024-05-10 |
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.
CVSS Score and Metrics +CVSS Score and Metrics -CVSS V3 Severity: | CVSS V2 Severity: |
CVSS Score : 7.5 | CVSS Score : |
Exploit Score: 3.9 | Exploit Score: |
Impact Score: 3.6 | Impact Score: |
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CVSS V3 Metrics: | CVSS V2 Metrics: |
Attack Vector: NETWORK | Access Vector: |
Attack Complexity: LOW | Access Complexity: |
Privileges Required: NONE | Authentication: |
User Interaction: NONE | Confidentiality: |
Scope: UNCHANGED | Integrity: |
Confidentiality: NONE | Availability: |
Integrity: NONE | |
Availability: HIGH | |
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