How severe is GHSA-7vww-mvcr-x6vj?

GHSA-7vww-mvcr-x6vj has a CVSS score of 5.9/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by GHSA-7vww-mvcr-x6vj?

GHSA-7vww-mvcr-x6vj affects the following packages: github.com/traefik/traefik/v3 (Go). Ecosystems affected: Go.

How do I fix GHSA-7vww-mvcr-x6vj?

Update github.com/traefik/traefik/v3 to 3.6.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-7vww-mvcr-x6vj is resolved across your whole dependency graph.

How do I detect GHSA-7vww-mvcr-x6vj in my Go dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/traefik/traefik/v3. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate GHSA-7vww-mvcr-x6vj if there is no patch (or I can't update yet)?

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.

How does O3 Security protect against GHSA-7vww-mvcr-x6vj?

O3 pinpoints whether GHSA-7vww-mvcr-x6vj is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is GHSA-7vww-mvcr-x6vj actively exploited in the wild?

No public exploit code has been indexed for GHSA-7vww-mvcr-x6vj yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for GHSA-7vww-mvcr-x6vj?

GHSA-7vww-mvcr-x6vj has an EPSS (Exploit Prediction Scoring System) score of 0.2%, placing it in the 10th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

When was GHSA-7vww-mvcr-x6vj published, and has it been updated?

GHSA-7vww-mvcr-x6vj was published on December 8, 2025 and was last updated on April 16, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐹 Go

GHSA-7vww-mvcr-x6vj

MEDIUM

Traefik Inverted TLS Verification Logic in ingress-nginx Provider

Also known asCVE-2025-66491GO-2025-4205

Published

Dec 8, 2025

Updated

Apr 16, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

EPSS Exploitation Probability

via FIRST.org ↗

0.2%probability of exploitation in next 30 days

Lower Risk10th percentile+0.20%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Blast Radius

1 pkg affected

🐹github.com/traefik/traefik/v3

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

Impact

There is a potential vulnerability in Traefik NGINX provider managing the nginx.ingress.kubernetes.io/proxy-ssl-verify annotation.

The provider inverts the semantics of the nginx.ingress.kubernetes.io/proxy-ssl-verify annotation. Setting the annotation to "on" (intending to enable backend TLS certificate verification) actually disables verification, allowing man-in-the-middle attacks against HTTPS backends when operators believe they are protected.

Patches

https://github.com/traefik/traefik/releases/tag/v3.6.3

For more information

If you have any questions or comments about this advisory, please open an issue.

<details> <summary>Original Description</summary>

Summary

A logic error in Traefik's experimental ingress-nginx provider inverts the semantics of the nginx.ingress.kubernetes.io/proxy-ssl-verify annotation. Setting the annotation to "on" (intending to enable backend TLS certificate verification) actually disables verification, allowing man-in-the-middle attacks against HTTPS backends when operators believe they are protected.

Details

In pkg/provider/kubernetes/ingress-nginx/kubernetes.go at line 512, the InsecureSkipVerify field is set using inverted logic:

nst := &namedServersTransport{
    Name: provider.Normalize(namespace + "-" + name),
    ServersTransport: &dynamic.ServersTransport{
        ServerName:         ptr.Deref(cfg.ProxySSLName, ptr.Deref(cfg.ProxySSLServerName, "")),
        InsecureSkipVerify: strings.ToLower(ptr.Deref(cfg.ProxySSLVerify, "off")) == "on",
    },
}

The expression == "on" evaluates to true when the annotation is "on", setting InsecureSkipVerify: true. In Go's crypto/tls, InsecureSkipVerify: true means "do not verify the server's certificate" — the opposite of what proxy-ssl-verify: "on" should do according to NGINX semantics.

Current behavior:

Annotation Value	InsecureSkipVerify	Actual Result
`"on"`	`true`	Verification disabled ❌
`"off"` (default)	`false`	Verification enabled

Expected behavior (per NGINX semantics):

Annotation Value	InsecureSkipVerify	Expected Result
`"on"`	`false`	Verification enabled
`"off"` (default)	`true`	Verification disabled

The test in pkg/provider/kubernetes/ingress-nginx/kubernetes_test.go lines 397-403 confirms this inverted behavior is codified as "expected":

ServersTransports: map[string]*dynamic.ServersTransport{
    "default-ingress-with-proxy-ssl": {
        ServerName:         "whoami.localhost",
        InsecureSkipVerify: true,  // Wrong: should be false when annotation is "on"
        RootCAs:            []types.FileOrContent{"-----BEGIN CERTIFICATE-----"},
    },
},

Affected versions: v3.5.0 through current master (introduced in commit 9bd5c617820f2a8d23b50b68d114bb7bc464eccd)

Pavel Kohout Aisle Research

</details>

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/traefik/traefik/v3`	≥ 3.5.0&&< 3.6.3	3.6.3

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/traefik/traefik/v3. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update github.com/traefik/traefik/v3 to 3.6.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-7vww-mvcr-x6vj is resolved across your whole dependency graph.
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.
How O3 protects you
O3 pinpoints whether GHSA-7vww-mvcr-x6vj is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-7vww-mvcr-x6vj. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

## Impact There is a potential vulnerability in Traefik NGINX provider managing the `nginx.ingress.kubernetes.io/proxy-ssl-verify` annotation. The provider inverts the semantics of the `nginx.ingress.kubernetes.io/proxy-ssl-verify` annotation. Setting the annotation to `"on"` (intending to enable backend TLS certificate verification) actually disables verification, allowing man-in-the-middle attacks against HTTPS backends when operators believe they are protected. ## Patches - https://github.com/traefik/traefik/releases/tag/v3.6.3 ## For more information If you have any questions or comm

O3 Security · Impact-Aware SCA

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