CVE-2020-11008
Description
A flaw was found in git where credentials can be leaked through the use of a crafted URL. The crafted URL must contain a newline, empty host, or lack a scheme so that the credential helper is fulled into giving the information of a different host to the client. The highest threat from this vulnerability is to data confidentiality.
Statement
Red Hat Enterprise Linux 6 is not affected by this flaw as the vulnerable version of git, version 1.7.9-rc0 and later, was never made available for this product.
Mitigation
The most complete workaround is to disable credential helpers altogether:
git config --unset credential.helper
git config --global --unset credential.helper
git config --system --unset credential.helper
An alternative is to avoid malicious URLs:
1. Examine the hostname and username portion of URLs fed to git clone or git fetch for the presence of encoded newlines (%0A) or syntactic oddities (e.g., http:///host with three slashes).
2. Avoid using submodules with untrusted repositories (don't use git clone --recurse-submodules; use git submodule update only after examining the URLs found in .gitmodules).
3. Avoid tools which may run git clone on untrusted URLs under the hood.
4. Avoid using the credential helper by only cloning publicly available repositories.
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 | High | High | N/A |
| Integrity Impact | None | None | N/A |
| Availability Impact | None | None | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/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.
Acknowledgements
Red Hat would like to thank the Git project for reporting this issue. Upstream acknowledges Carlo Arenas as the original reporter.
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