CVE-2020-10543
Description
From CVE.org
Perl before 5.30.3 on 32-bit platforms allows a heap-based buffer overflow because nested regular expression quantifiers have an integer overflow.
Statement
A heap buffer overflow vulnerability exists in the regular expression compiler of Perl packages shipped with Red Hat Enterprise Linux 6, 7, and 8. The flaw occurs in the S_study_chunk() function of regcomp.c due to a signed size_t integer overflow in storage space calculations for nested regular expression quantifiers. When untrusted regular expressions are compiled, this can lead to out-of-bounds memory writes with attacker-controlled data. The vulnerability does not depend on the data being matched, but rather on the regular expression itself. On Red Hat systems, this could result in denial of service or potential code execution when processing malicious regular expressions. Red Hat customers should not allow untrusted regular expressions to be compiled by the Perl regular expression compiler, as regular expressions in Perl can contain arbitrary code.
Mitigation
To mitigate this flaw, developers should not allow untrusted regular expressions to be compiled by the Perl regular expression compiler.
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 | 8.2 | 8.2 | N/A |
| Attack Vector | Network | Network | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | None | None | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | None | None | N/A |
| Integrity Impact | Low | Low | N/A |
| Availability Impact | High | High | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
Red Hat CVSS v3 Score Explanation
Marked C:N as this is an out-of-bounds write which could affect integrity or most likely, availability, but it is not likely to affect confidentiality. Exploiting this flaw could pose a low risk to integrity of data due to limited write capability.
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart; DoS: Resource Consumption (Memory); DoS: Instability
This weakness can generally lead to undefined behavior and therefore crashes. When the calculated result is used for resource allocation, this weakness can cause too many (or too few) resources to be allocated, possibly enabling crashes if the product requests more resources than can be provided.
Integrity
Technical Impact: Modify Memory
If the value in question is important to data (as opposed to flow), simple data corruption has occurred. Also, if the overflow/wraparound results in other conditions such as buffer overflows, further memory corruption may occur.
Confidentiality,Availability,Access Control
Technical Impact: Execute Unauthorized Code or Commands; Bypass Protection Mechanism
This weakness can sometimes trigger buffer overflows, which can be used to execute arbitrary code. This is usually outside the scope of the product's implicit security policy.
Availability,Other
Technical Impact: Alter Execution Logic; DoS: Crash, Exit, or Restart; DoS: Resource Consumption (CPU)
If the overflow/wraparound occurs in a loop index variable, this could cause the loop to terminate at the wrong time - too early, too late, or not at all (i.e., infinite loops). With too many iterations, some loops could consume too many resources such as memory, file handles, etc., possibly leading to a crash or other DoS.
Access Control
Technical Impact: Bypass Protection Mechanism
If integer values are used in security-critical decisions, such as calculating quotas or allocation limits, integer overflows can be used to cause an incorrect security decision.
Acknowledgements
Red Hat would like to thank ManhND (Tarantula Team) and VinCSS (Vingroup) for reporting this issue.
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