CVE-2019-3858
Description
An out of bounds read flaw was discovered in libssh2 when a specially crafted SFTP packet is received from the server. A remote attacker who compromises a SSH server may be able to cause a denial of service or read data in the client memory.
Statement
This flaw was present in libssh2 packages included in Red Hat Virtualization Hypervisor and Management Appliance, however libssh2 in these hosts is never exposed to malicious clients or servers.
libssh2 is no longer included in the virt module since Red Hat Enterprise Linux 8.1.
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 | 9.1 | N/A |
| Attack Vector | Network | Network | N/A |
| Attack Complexity | High | Low | N/A |
| Privileges Required | None | None | N/A |
| User Interaction | Required | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | Low | High | N/A |
| Integrity Impact | Low | None | N/A |
| Availability Impact | Low | High | N/A |
Vector
Red Hat: CVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:L
NVD: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
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.
Acknowledgements
Red Hat would like to thank the libssh2 project for reporting this issue. Upstream acknowledges Chris Coulson (Canonical Ltd.) as the original reporter.
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