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Symlink following allows leaking out-of-bounds YAML files from Argo CD repo-server

Moderate
crenshaw-dev published GHSA-q4w5-4gq2-98vm Jun 21, 2022

Package

gomod github.com/argoproj/argo-cd (Go)

Affected versions

1.3.0 through 2.1.15, 2.2.9, 2.3.4, 2.4.0

Patched versions

2.1.16, 2.2.10, 2.3.5, 2.4.1

Description

Impact

All unpatched versions of Argo CD starting with v1.3.0 are vulnerable to a symlink following bug allowing a malicious user with repository write access to leak sensitive YAML files from Argo CD's repo-server.

A malicious Argo CD user with write access for a repository which is (or may be) used in a Helm-type Application may commit a symlink which points to an out-of-bounds file. If the target file is a valid YAML file, the attacker can read the contents of that file.

Sensitive files which could be leaked include manifest files from other Applications' source repositories (potentially decrypted files, if you are using a decryption plugin) or any YAML-formatted secrets which have been mounted as files on the repo-server.

Patches

A patch for this vulnerability has been released in the following Argo CD versions:

  • v2.4.1
  • v2.3.5
  • v2.2.10
  • v2.1.16

Workarounds

Mitigations

  • Avoid mounting YAML-formatted secrets as files on the repo-server.
  • Upgrade to >=2.3.0 to significantly reduce the risk of leaking out-of-bounds manifest files. Starting with 2.3.0, repository paths are randomized, and read permissions are restricted when manifests are not being actively being generated. This makes it very difficult to craft and use a malicious symlink.

Best practices which can mitigate risk

  • Limit who has push access to manifest repositories.
  • Limit who is allowed to configure new source repositories.

Credits

Disclosed by ADA Logics in a security audit of the Argo project sponsored by CNCF and facilitated by OSTIF. Thanks to Adam Korczynski and David Korczynski for their work on the audit.

References

For more information

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

CVE ID

CVE-2022-31036

Credits