CVE-2021-3910: Github.com/cloudflare/cfrpki NUL Character Vulnerability

HIGH
Advisory Identifier: GHSA-5mxh-2qfv-4g7j
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CVSS 7.5
CWE-20
Published
Advisory Summary

CVE-2021-3910 is a HIGH (CVSS 7.5) nul character vulnerability (CWE-20: Improper Input Validation) affecting Github.com/cloudflare/cfrpki libraries in the Go ecosystem. The issue involves nul character in roa causes octorpki to crash. Remediation is available by upgrading affected packages to version 1.4.0.

CVE-2021-3910 at a Glance

CVE Identifier CVE-2021-3910
GHSA Identifier GHSA-5mxh-2qfv-4g7j
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-20: Improper Input Validation
Affected Product Github.com/cloudflare/cfrpki
Package Ecosystem Go
Published Date
Last Updated

Security Impact

CVSS: 7.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity None (I:N)
Availability High (A:H)

How to Fix CVE-2021-3910

To remediate this vulnerability, upgrade all affected Github.com/cloudflare/cfrpki dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

github.com/cloudflare/cfrpki fixed: 1.4.0 
Upgrade github.com/cloudflare/cfrpki to 1.4.0
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for github.com/cloudflare/cfrpki

How to Check if You Are Affected

To determine whether your application is affected by CVE-2021-3910, inspect your project dependencies for Github.com/cloudflare/cfrpki:

inspect dependencies for github.com/cloudflare/cfrpki

Analyze the terminal output to locate any version of Github.com/cloudflare/cfrpki in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.4.0), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-20: Improper Input Validation, where the product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. In Github.com/cloudflare/cfrpki, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

OctoRPKI crashes when encountering a repository that returns an invalid ROA (just an encoded `NUL` (`\0`) character). ## Patches ## For more information If you have any questions or comments about this advisory email us at security@cloudflare.com

CVE-2021-3910 Affected Github.com/cloudflare/cfrpki Versions

1 component(s)
Fixed Versions:
1.4.0
Product / Package Ecosystem Affected Versions Fixed Version
github.com/cloudflare/cfrpki
golang/github.com/cloudflare/cfrpki
Go
< 1.4.0
1.4.0

References

GitHub Advisory / Wiki ADVISORY
https://github.com/cloudflare/cfrpki/security/advisories/GHSA-5mxh-2qfv-4g7j
NVD — CVE-2021-3910 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-3910
Security Fix Commit FIX COMMIT
https://github.com/cloudflare/cfrpki/commit/76f0f7a98da001fa04e5bc0407c6702f91096bfa
Github.com/cloudflare/cfrpki Source Repository REPOSITORY
https://github.com/cloudflare/cfrpki
Github.com/cloudflare/cfrpki Release RELEASE
https://github.com/cloudflare/cfrpki/releases/tag/v1.4.0
pkg.go.dev/vuln/go-2022-0251 WEB
https://pkg.go.dev/vuln/GO-2022-0251
Github.com/cloudflare/cfrpki Security Information SECURITY
https://www.debian.org/security/2022/dsa-5041

Frequently Asked Questions

What is CVE-2021-3910?
CVE-2021-3910 is a security vulnerability in Github.com/cloudflare/cfrpki involving NUL character in ROA causes OctoRPKI to crash under CWE-20: Improper Input Validation.
Which Github.com/cloudflare/cfrpki versions are affected?
Affected versions include releases prior to 1.4.0 across affected packages: github.com/cloudflare/cfrpki.
What version fixes CVE-2021-3910?
Upgrading to 1.4.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is github.com/cloudflare/cfrpki affected?
Yes, github.com/cloudflare/cfrpki is affected in releases prior to 1.4.0. Upgrade your dependency to 1.4.0 or later.
What is the CVSS score of CVE-2021-3910?
CVE-2021-3910 has a CVSS v3.1 base score of 7.5 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
What CWE is associated with CVE-2021-3910?
CVE-2021-3910 is classified under CWE-20: Improper Input Validation (The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.).
How can I check Go dependencies for CVE-2021-3910?
Run the dependency tree command: 'inspect dependencies for github.com/cloudflare/cfrpki'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-5mxh-2qfv-4g7j",
  "modified" : "2026-04-15T21:11:17Z",
  "published" : "2021-11-10T20:15:06Z",
  "aliases" : [ "CVE-2021-3910" ],
  "summary" : "NUL character in ROA causes OctoRPKI to crash",
  "details" : "OctoRPKI crashes when encountering a repository that returns an invalid ROA (just an encoded `NUL` (`\\0`) character).\n\n## Patches\n\n## For more information\nIf you have any questions or comments about this advisory email us at security@cloudflare.com",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/cloudflare/cfrpki"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.4.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/cloudflare/cfrpki/security/advisories/GHSA-5mxh-2qfv-4g7j"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-3910"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/cloudflare/cfrpki/commit/76f0f7a98da001fa04e5bc0407c6702f91096bfa"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/cloudflare/cfrpki"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/cloudflare/cfrpki/releases/tag/v1.4.0"
  }, {
    "type" : "WEB",
    "url" : "https://pkg.go.dev/vuln/GO-2022-0251"
  }, {
    "type" : "WEB",
    "url" : "https://www.debian.org/security/2022/dsa-5041"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-20" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-11-10T18:17:39Z",
    "nvd_published_at" : "2021-11-11T22:15:00Z"
  }
}