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Istio Fragments in Path May Lead to Authorization Policy Bypass

High severity GitHub Reviewed Published Aug 24, 2021 in istio/istio • Updated Jan 27, 2023

Package

gomod istio.io/istio (Go)

Affected versions

< 1.9.8
>= 1.10.0, < 1.10.4
= 1.11.0

Patched versions

1.9.8
1.10.4
1.11.1

Description

Impact

Istio 1.11.0, 1.10.3 and below, and 1.9.7 and below contain a remotely exploitable vulnerability where an HTTP request with #fragment in the path may bypass Istio’s URI path based authorization policies.

Patches

  • Istio 1.11.1 and above
  • Istio 1.10.4 and above
  • Istio 1.9.8 and above

Workarounds

A Lua filter may be written to normalize the path. This is similar to the Path normalization presented in the Security Best Practices guide.

References

More details can be found in the Istio Security Bulletin

For more information

If you have any questions or comments about this advisory, please email us at istio-security-vulnerability-reports@googlegroups.com

References

@brian-avery brian-avery published to istio/istio Aug 24, 2021
Published by the National Vulnerability Database Aug 24, 2021
Reviewed Aug 25, 2021
Published to the GitHub Advisory Database Aug 30, 2021
Last updated Jan 27, 2023

Severity

High

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
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
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:R/S:U/C:H/I:H/A:N

EPSS score

0.167%
(54th percentile)

Weaknesses

CVE ID

CVE-2021-39156

GHSA ID

GHSA-hqxw-mm44-gc4r

Source code

Credits

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