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HIGH severity

CVE-2019-14243 — proxyprotocol

HIGHFix: mastercactapus/proxyprotocol@5c4a101

CVE-2019-14243 is a high-severity (CVSS 7.5) Improper Input Validation vulnerability in github.com/mastercactapus/proxyprotocol. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for github.com/mastercactapus/proxyprotocol — see the affected versions and patch details below.

mastercactapus proxyprotocol vulnerable to denial of service

Also known asGHSA-85c5-ccm8-vr96GO-2023-1923
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
1 known
Exploitation data as of Nov 2, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
4.3%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs91th percentile — riskier than 91% of all scored CVEsHighest risk
0.00%1.82%3.65%5.47%0.4%4.3%May 26Sep 26Nov 26

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

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected
🐹github.com/mastercactapus/proxyprotocol

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

headerv2.go in mastercactapus proxyprotocol before 0.0.2, as used in the mastercactapus caddy-proxyprotocol plugin through 0.0.2 for Caddy, allows remote attackers to cause a denial of service (webserver panic and daemon crash) via a crafted HAProxy PROXY v2 request with truncated source/destination address data.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐹Gogithub.com/mastercactapus/proxyprotocolall versions0.0.2go get github.com/mastercactapus/proxyprotocol@v0.0.2

Affected Products

1 product · 1 configurations
Application
proxyprotocolhaproxy
< 0.0.2
range
Exploits & PoCs
1

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

headerv2.go in mastercactapus proxyprotocol before 0.0.2, as used in the…

github.comNVDDec 2019

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/mastercactapus/proxyprotocol, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update github.com/mastercactapus/proxyprotocol to 0.0.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2019-14243 is resolved across your whole dependency graph.

  3. Workarounds

    Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Frequently Asked Questions

headerv2.go in mastercactapus proxyprotocol before 0.0.2, as used in the mastercactapus caddy-proxyprotocol plugin through 0.0.2 for Caddy, allows remote attackers to cause a denial of service (webserver panic and daemon crash) via a crafted HAProxy PROXY v2 request with truncated source/destination address data.
O3 Security · Impact-Aware SCA

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CVE-2019-14243: proxyprotocol DoS — Fixed in 0.0.2