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HIGH severity

CVE-2021-42583 — maddy

HIGH

CVE-2021-42583 is a high-severity (CVSS 7.5) Broken Cryptographic Algorithm vulnerability in github.com/foxcpp/maddy. A fix is available for github.com/foxcpp/maddy — see the affected versions and patch details below.

Use of a Broken or Risky Cryptographic Algorithm in Max Mazurov Maddy

Also known asGHSA-5r5w-h76p-m726GO-2022-0306
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Oct 13, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
0.7%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs53th percentile — riskier than 53% of all scored CVEsHighest risk
0.00%0.41%0.82%1.22%0.1%0.7%Apr 26Aug 26Oct 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2021-42583 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 388,997 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected
🐹github.com/foxcpp/maddy

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

A Broken or Risky Cryptographic Algorithm exists in Max Mazurov Maddy before 0.5.2, which is an unnecessary risk that may result in the exposure of sensitive information.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐹Gogithub.com/foxcpp/maddyall versions0.5.2go get github.com/foxcpp/maddy@v0.5.2

Affected Products

1 product · 1 configurations
Application
maddyfoxcpp
< 0.5.2
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/foxcpp/maddy, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update github.com/foxcpp/maddy to 0.5.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-42583 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

A Broken or Risky Cryptographic Algorithm exists in Max Mazurov Maddy before 0.5.2, which is an unnecessary risk that may result in the exposure of sensitive information.
O3 Security · Impact-Aware SCA

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CVE-2021-42583: maddy — Fixed in 0.5.2