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CVE-2021-3761

25
FAUCET Score

CVE-2021-3761 is a high-severity vulnerability affecting OctoRPKI prior to version 1.3.0, and consequently Cloudflare and Debian systems utilizing it. An attacker can exploit this by crafting a malicious RPKI CA issuer, causing OctoRPKI to emit invalid VRP "MaxLength" values. This leads to RTR session termination, effectively disabling RPKI Origin Validation and potentially enabling BGP hijacks that would otherwise be rejected. The vulnerability has a CVSS score of 7.5 (High) due to its network-based attack vector, low complexity, and high impact on availability. There is currently no public exploit code, no evidence of active exploitation, and minimal community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 1.3.0CPE matchmatch criteria
cpe:2.3:a:cloudflare:octorpki:*:*:*:*:*:*:*:*
11.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.5HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.22%
Probability of exploitation in next 30 days
EPSS Percentile
65.4%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0122 is in the 44th percentile among its peer group of 51,506 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (2)

github_advisorypatch availablevia nvd_reference
View patch
gopatch availablevia ghsa
Product: github.com/cloudflare/cfrpkiFixed in: 1.3.0

Vendor Advisories (1)

goGHSA-c8xp-8mf3-62h9high

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

Sep 7, 2021

References

github.com / cloudflare/cfrpki/security/advisories/GHSA-c8xp-8mf3-62h9
PatchThird Party Advisory
debian.org / security/2022/dsa-5041
Third Party Advisory