CVE-2021-3903
Description
From CVE.org
vim is vulnerable to Heap-based Buffer Overflow
Statement
This flaw is marked as Low Impact because it requires a user to run an untrusted/malicious Vim script using the -s option at the command line. Untrusted Vim scripts should never be run as they can already execute arbitrary shell commands. The security issue raised by this flaw would be no worse than what is already possible when running untrusted Vim scripts.
Vim as shipped in Red Hat Enterprise Linux 8 is not affected by this flaw. The flaw is out of support scope for Red Hat Enterprise Linux 6 and 7.
Mitigation
Do not run untrusted vim scripts with -s {scriptin} as it is never safe to do so.
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 | 5.5 | 7.8 | 7.3 |
| Attack Vector | Local | Local | Local |
| Attack Complexity | Low | Low | Low |
| Privileges Required | None | Low | None |
| User Interaction | Required | None | Required |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | None | High | Low |
| 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:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
cve.org: CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:H/A:H
Red Hat CVSS v3 Score Explanation
C:N and I:N as this is an out-of-bounds READ and Vim does not automatically send read contents to a network location, therefore the risk here is to availability rather than integrity or confidentiality.
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Memory
An attacker could get secret values such as cryptographic keys, PII, memory addresses, or other information that could be used in additional attacks.
Confidentiality
Technical Impact: Bypass Protection Mechanism
Out-of-bounds memory could contain memory addresses or other information that can be used to bypass ASLR and other protection mechanisms in order to improve the reliability of exploiting a separate weakness for code execution.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
An attacker could cause a segmentation fault or crash by causing memory to be read outside of the bounds of the buffer. This is especially likely when the code reads a variable amount of data and assumes that a sentinel exists to stop the read operation, such as a NUL in a string.
Other
Technical Impact: Varies by Context
The read operation could produce other undefined or unexpected results.
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