CVE-2016-3115
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Last Modified:
Description
It was discovered that the OpenSSH server did not sanitize data received in requests to enable X11 forwarding. An authenticated client with restricted SSH access could possibly use this flaw to bypass intended restrictions.
Mitigation
Set X11Forwarding=no in sshd_config.
For authorized_keys that specify a "command" restriction, this issue can be mitigated by also setting the "no-X11-forwarding" restriction. In OpenSSH 7.2 and later, the "restrict" restriction can be used instead, which includes the "no-X11-forwarding" restriction.
Additional information
- Bugzilla 1316829: openssh: missing sanitisation of input for X11 forwarding
- CWE-20: Improper Input Validation
- FAQ: Frequently asked questions about CVE-2016-3115
Common Vulnerability Scoring System (CVSS) Score Details
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).
| Red Hat | NVD | |
|---|---|---|
CVSS v2 Base Score | 4.9 | 5.5 |
Attack Vector | Network | Network |
Access Complexity | Medium | Low |
Authentication | Single | Single |
Confidentiality Impact | Partial | Partial |
Integrity Impact | Partial | Partial |
Availability Impact | None | None |
CVSS v2 Vector
Red Hat: AV:N/AC:M/Au:S/C:P/I:P/A:N
NVD: AV:N/AC:L/Au:S/C:P/I:P/A:N
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart; DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory)
An attacker could provide unexpected values and cause a program crash or arbitrary control of resource allocation, leading to excessive consumption of resources such as memory and CPU.
Confidentiality
Technical Impact: Read Memory; Read Files or Directories
An attacker could read confidential data if they are able to control resource references.
Integrity,Confidentiality,Availability
Technical Impact: Modify Memory; Execute Unauthorized Code or Commands
An attacker could use malicious input to modify data or possibly alter control flow in unexpected ways, including arbitrary command execution.
Frequently Asked Questions
Why is Red Hat's CVSS v3 score or Impact different from other vendors?
My product is listed as "Under investigation" or "Affected", when will Red Hat release a fix for this vulnerability?
What can I do if my product is listed as "Will not fix"?
What can I do if my product is listed as "Fix deferred"?
What is a mitigation?
I have a Red Hat product but it is not in the above list, is it affected?
Why is my security scanner reporting my product as vulnerable to this vulnerability even though my product version is fixed or not affected?
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