CVE-2020-20703
Description
A use-after-free flaw was found in Vim. This issue allows a heap buffer overflow leading to a write access violation. This flaw allows the attacker to possibly have control over the write address and value, which may lead to an application crash.
Statement
Red Hat Product Security has rated this issue as having a Low security impact, because the "victim" has to run an untrusted file IN SCRIPT MODE. Someone who is running untrusted files in script mode is equivalent to someone just taking a random python script and running it.
For additional information, refer to the Issue Severity Classification: https://access.redhat.com/security/updates/classification/
Mitigation
Untrusted vim scripts with -s [scriptin] are not recommended to run.
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).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.5 | 9.8 | 9.8 |
| Attack Vector | Local | Network | Network |
| Attack Complexity | Low | Low | Low |
| Privileges Required | None | None | None |
| User Interaction | Required | None | None |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | None | High | High |
| Integrity Impact | None | High | High |
| Availability Impact | High | High | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Red Hat CVSS v3 Score Explanation
AV:L, because, though the attacker might pass malicious scripted file to "Vim" remotely or locally, But according to "first.org - cvss-v3.1-user-guide": The vulnerabilities which require user interaction to download or receive malicious content over network (which could also be delivered locally, e.g., via USB drives) should be scored as Local.
UI:R, because, in order to open/pass the specially crafted script containing malicious junk input to "Vim", the user interaction is required.
Understanding the Weakness (CWE)
Integrity
Technical Impact: Modify Memory; Execute Unauthorized Code or Commands
Write operations could cause memory corruption. In some cases, an adversary can modify control data such as return addresses in order to execute unexpected code.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
Attempting to access out-of-range, invalid, or unauthorized memory could cause the product to crash.
Other
Technical Impact: Unexpected State
Subsequent write operations can produce undefined or unexpected results.
Frequently Asked Questions
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