CVE-2026-101087

MEDIUM
Published Sep 27, 2026 Modified Sep 30, 2026 CWE-918

Description

Nezha versions 2.0.10 through 2.3.2 use a restricted HTTP client to validate user-configurable notification and DDNS webhook URLs, but the denylist did not cover IPv6 transition ranges — specifically the 6to4 prefix 2002::/16 and the local-use IPv4/IPv6 translation prefix 64:ff9b:1::/48. Because such addresses satisfy Go's netip.Addr.IsGlobalUnicast check, the URL validator accepted them. An authenticated user able to configure a webhook may be able to cause the dashboard to issue requests to an otherwise restricted IPv6 endpoint, but only where the dashboard's network provides unusual or non-standards-compliant routing for these transition ranges; no direct path to an IPv4 metadata, loopback, or private-network HTTP request has been demonstrated. The issue is fixed in version 2.3.3 (commit d1fcde8e), which blocks both prefixes.

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CVSS v3.1 Score

4.3
MEDIUM
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

EPSS — Exploit Prediction

0.0026
Probability of exploitation
0.16%
Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-918 Server-Side Request Forgery (SSRF)

References

Frequently Asked Questions

What is CVE-2026-101087? +
Nezha versions 2.0.10 through 2.3.2 use a restricted HTTP client to validate user-configurable notification and DDNS webhook URLs, but the denylist did not cover IPv6 transition ranges — specifically the 6to4 prefix 2002::/16 and the local-use IPv4/IPv6 translation prefix 64:ff9b:1::/48. Because such addresses satisfy Go's netip.Addr.IsGlobalUnicast check, the URL validator accepted them. An authenticated user able to configure a webhook may be able to cause the dashboard to issue requests to an otherwise restricted IPv6 endpoint, but only where the dashboard's network provides unusual or non-standards-compliant routing for these transition ranges; no direct path to an IPv4 metadata, loopback, or private-network HTTP request has been demonstrated. The issue is fixed in version 2.3.3 (commit d1fcde8e), which blocks both prefixes. It has a CVSS v3.1 base score of 4.3 (MEDIUM).
How severe is CVE-2026-101087? +
CVE-2026-101087 has a CVSS v3.1 score of 4.3 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0026, placing it in the 0th percentile for exploitation probability.
How do I check if I'm vulnerable to CVE-2026-101087? +
You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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