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

CVE-2021-3761 → View on GitHub ↗ View on CVE.org ↗ View on NVD ↗

Description

Any CA issuer in the RPKI can trick OctoRPKI prior to https://github.com/cloudflare/cfrpki/commit/a8db4e009ef217484598ba1fd1c595b54e0f6422 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

https://github.com/cloudflare/cfrpki/commit/a8db4e009ef217484598ba1fd1c595b54e0f6422

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

For more information

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Basic information

Type
reviewed
Severity
high
Advisory on GitHub
Open advisory ↗
Repository advisory
Open repository advisory ↗
Source code
Browse source ↗
Published (advisory)
2021-09-07 23:02:18 UTC
Updated
2023-02-14 17:45:21 UTC
GitHub reviewed
2021-09-03 21:40:39 UTC
NVD published
2021-09-09 14:15:00 UTC

EPSS Score

Score Percentile
0.45% 63.55%

CVSS Scores

Base score Version Severity Vector
7.5 3.1 —
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.

Identifiers

Type Value
GHSA GHSA-c8xp-8mf3-62h9 ↗
CVE CVE-2021-3761 ↗

CWEs

CWE id Name
CWE-295 Improper Certificate Validation
CWE-787 Out-of-bounds Write

Credits

  • job (analyst)

Affected packages (1)

Vulnerable version ranges and first patched releases as published by GitHub.

Ecosystem Package Vulnerable range First patched Vulnerable functions
go github.com/cloudflare/cfrpki < 1.3.0 1.3.0 —

References

cvelogic Threat Intelligence