CVE-2020-29652
Description
A null pointer dereference vulnerability was found in golang. When using the library's ssh server without specifying an option for GSSAPIWithMICConfig, it is possible for an attacker to craft an ssh client connection using the gssapi-with-mic authentication method and cause the server to panic resulting in a denial of service. The highest threat from this vulnerability is to system availability.
Statement
A large number of products include the affected package, but do not make use of the vulnerable SSH server code. Accordingly, the flaw itself is rated as "Important", but these products themselves all have a "Low" severity rating.
Additionally, a number of products include golang.org/x/crypto (or even golang.org/x/crypto/ssh/terminal) but not specifically golang.org/x/crypto/ssh/server.go in the final build. As this would result in a very large number of entries of not affected products, only products which include the ssh server code (golang.org/x/crypto/ssh/server.go) have been represented here.
Red Hat Enterprise Linux 8 container-tools:rhel8/containernetworking-plugins is not affected because although it uses some functionality from golang.org/x/crypto, it does not use or import anything from golang.org/x/crypto/ssh/*.
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 | 7.5 | 7.5 | N/A |
| Attack Vector | Network | Network | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | None | None | 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:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD: CVSS:3.1/AV:N/AC:L/PR:N/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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