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HIGH severity

CVE-2019-12243 — istio

HIGHFix: istio/istio#13893

CVE-2019-12243 is a high-severity (CVSS 7.5) vulnerability in istio.io/istio. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for istio.io/istio — see the affected versions and patch details below.

Istio may not check inbound TCP connections against istio-policy

Also known asGHSA-6g5f-f5pm-mjrg
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
1 known
Exploitation data as of Nov 8, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
1.2%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs68th percentile — riskier than 68% of all scored CVEsHighest risk
0.00%0.56%1.12%1.68%0.1%1.2%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
🐹istio.io/istio

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

Istio 1.1.x through 1.1.6 has Incorrect Access Control. When disablePolicyChecks is set to false, inbound TCP connections do not generate Check requests to istio-policy and external authorization is not applied.

This behavior is a result of a change to istio/pilot/pkg/networking/plugin/mixer/mixer.go in 1.1.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐹Goistio.io/istio≥ 1.1.0&&< 1.1.71.1.7go get istio.io/istio@v1.1.7

Affected Products

1 product · 1 configurations
Application
istioistio
≥ 1.1 && ≤ 1.1.6
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.

Istio 1.1.x through 1.1.6 has Incorrect Access Control.

istio.ioNVDAug 2020

Detection & mitigation playbook

Open-source dependency

  1. Detect

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

  2. Fix

    Update istio.io/istio to 1.1.7 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2019-12243 is resolved across your whole dependency graph.

  3. Workarounds

    Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Frequently Asked Questions

Istio 1.1.x through 1.1.6 has Incorrect Access Control. When `disablePolicyChecks` is set to `false`, inbound TCP connections do not generate Check requests to istio-policy and external authorization is not applied. This behavior is a result of a change to `istio/pilot/pkg/networking/plugin/mixer/mixer.go` in 1.1.
O3 Security · Impact-Aware SCA

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CVE-2019-12243: istio — Fixed in 1.1.7