CVE-2022-40674
Description
A vulnerability was found in expat. With this flaw, it is possible to create a situation in which parsing is suspended while substituting in an internal entity so that XML_ResumeParser directly uses the internalEntityProcessor as its processor. If the subsequent parse includes some unclosed tags, this will return without calling storeRawNames to ensure that the raw versions of the tag names are stored in memory other than the parse buffer itself. Issues occur if the parse buffer is changed or reallocated (for example, if processing a file line by line), problems occur. Using this vulnerability in the doContent function allows an attacker to triage a denial of service or potentially arbitrary code execution.
Statement
This flaw is rated as important because this flaw can easily compromise the confidentiality, integrity, or availability of resources but a successful attack can not execute arbitrary code, or allow remote users to cause a denial of service because attack complexity is high and depends on conditions beyond the attacker's control.
Mitigation
There is no known mitigation other than restricting applications using the expat library from processing XML content. Please update the affected packages as soon as possible.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 8.1 | 8.1 | 8.1 |
| Attack Vector | Network | Network | Network |
| Attack Complexity | High | High | High |
| Privileges Required | None | None | None |
| User Interaction | None | None | None |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | High | High | High |
| Integrity Impact | High | High | High |
| Availability Impact | High | High | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
cve.org: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Red Hat CVSS v3 Score Explanation
Attack Complexity is high because a successful attack depends on conditions beyond the attacker's control.
Understanding the Weakness (CWE)
Integrity
Technical Impact: Modify Memory
The use of previously freed memory may corrupt valid data, if the memory area in question has been allocated and used properly elsewhere.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
If chunk consolidation occurs after the use of previously freed data, the process may crash when invalid data is used as chunk information.
Confidentiality
Technical Impact: Read Memory
Read operations on freed memory can sometimes leak sensitive information instead of causing a crash
Integrity,Confidentiality,Availability
Technical Impact: Execute Unauthorized Code or Commands
If malicious data is entered before chunk consolidation can take place, it may be possible to take advantage of a write-what-where primitive to execute arbitrary code. If the newly allocated data happens to hold a class, in C++ for example, various function pointers may be scattered within the heap data. If one of these function pointers is overwritten with an address to valid shellcode, execution of arbitrary code can be achieved.
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