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Smokescreen SSRF via deny list bypass (square brackets)

Moderate severity GitHub Reviewed Published May 10, 2022 in stripe/smokescreen • Updated Jan 27, 2023

Package

gomod github.com/stripe/smokescreen (Go)

Affected versions

< 0.0.4

Patched versions

0.0.4

Description

Impact

The primary use case for Smokescreen is to prevent server-side request forgery (SSRF) attacks in which external attackers leverage the behavior of applications to connect to or scan internal infrastructure.

Smokescreen also offers an option to deny access to additional (e.g., external) URLs by way of a deny list. There was an issue in Smokescreen that made it possible to bypass the deny list feature by surrounding the hostname with square brackets (e.g. [example.com]).

Recommendation

Upgrade Smokescreen to version 0.0.4 or later.

Acknowledgements

Thanks to Axel Chong for reporting the issue.

For more information

Email us at [email protected]

References

@jjiang-stripe jjiang-stripe published to stripe/smokescreen May 10, 2022
Published by the National Vulnerability Database May 21, 2022
Published to the GitHub Advisory Database May 24, 2022
Reviewed May 24, 2022
Last updated Jan 27, 2023

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
None
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:N/UI:N/S:U/C:L/I:N/A:N

EPSS score

0.081%
(35th percentile)

Weaknesses

CVE ID

CVE-2022-29188

GHSA ID

GHSA-qwrf-gfpj-qvj6

Source code

github.com/stripe/smokescreen

Credits

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