CVE-2020-12866
Description
From CVE.org
A NULL pointer dereference in SANE Backends before 1.0.30 allows a malicious device connected to the same local network as the victim to cause a denial of service, GHSL-2020-079.
Statement
The vulnerable code is a part of "driver for Epson ESC/I-2 scanners" which was first introduced in sane-backends-1.0.25. (via https://gitlab.com/sane-project/backends/-/commit/d72f4663c0ad6e6f779c15c8baf5f92b675ae19a) Therefore only versions of sane-backends shipped with Red Hat Enterprise Linux 8 is affected by this flaw.
Mitigation
This flaw can be mitigated by limiting network scanner discovery to a trusted subnet via the "net" configuration in the "/etc/sane.d/epsonds.conf" configuration file. Also automatic network scanner discovery can be turned off by commenting out the line "net autodiscovery" in the same configuration file.
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 | 5.7 | 5.7 | N/A |
| Attack Vector | Adjacent Network | Adjacent Network | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | Low | Low | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | None | None | N/A |
| Integrity Impact | None | None | N/A |
| Availability Impact | High | High | N/A |
Vector
Red Hat: CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
NVD: CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart
NULL pointer dereferences usually result in the failure of the process unless exception handling (on some platforms) is available and implemented. Even when exception handling is being used, it can still be very difficult to return the software to a safe state of operation.
Integrity,Confidentiality
Technical Impact: Execute Unauthorized Code or Commands; Read Memory; Modify Memory
In rare circumstances, when NULL is equivalent to the 0x0 memory address and privileged code can access it, then writing or reading memory is possible, which may lead to code execution.
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