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OctoRPKI lacks contextual out-of-bounds check when validating RPKI ROA maxLength values

High severity GitHub Reviewed Published Sep 3, 2021 in cloudflare/cfrpki • Updated Feb 14, 2023

Package

gomod github.com/cloudflare/cfrpki (Go)

Affected versions

< 1.3.0

Patched versions

1.3.0

Description

Any CA issuer in the RPKI can trick OctoRPKI prior to cloudflare/cfrpki@a8db4e0 into emitting an invalid VRP "MaxLength" value, causing RTR sessions to terminate.

Impact

An attacker can use this to disable RPKI Origin Validation in a victim network (for example AS 13335 - Cloudflare) prior to launching a BGP hijack which during normal operations would be rejected as "RPKI invalid". Additionally, in certain deployments RTR session flapping in and of itself also could cause BGP routing churn, causing availability issues.

Patches

cloudflare/cfrpki@a8db4e0

https://github.com/cloudflare/cfrpki/releases/tag/v1.3.0

For more information

If you have any questions or comments about this advisory:

References

@dhaynespls dhaynespls published to cloudflare/cfrpki Sep 3, 2021
Reviewed Sep 3, 2021
Published to the GitHub Advisory Database Sep 7, 2021
Published by the National Vulnerability Database Sep 9, 2021
Last updated Feb 14, 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
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

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:N/I:N/A:H

EPSS score

0.114%
(46th percentile)

Weaknesses

CVE ID

CVE-2021-3761

GHSA ID

GHSA-c8xp-8mf3-62h9

Source code

github.com/cloudflare/cfrpki

Credits

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