What’s Vulnerable › Vulnerabilities

CVE-2026-62999: Copier: Percent-encoded dot segments in template URLs can allow trusted-prefix escape (Incomplete fix for trust-prefix bypass)

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-07-31 · updated 2026-10-23
• Weakness: CWE-22

Description

Copier is a library and CLI app for rendering project templates. From 9.5.0 through 9.16.0, percent-encoded parent-directory segments or encoded path separators in a template URL can match a configured trusted repository prefix before an HTTP server or Git transport decodes the path, allowing unsafe template features from a repository outside the trusted prefix to run after user interaction. This issue is fixed in version 9.17.0.

Affected products

• copier-org copier: from 9.5.0, <= 9.16.0

References

• https://github.com/copier-org/copier/commit/7408f0d6287a7bf452715fd9f25dc54eaba3c295
• https://github.com/copier-org/copier/releases/tag/v9.17.0
• https://github.com/copier-org/copier/security/advisories/GHSA-34mv-rjq9-5mch
• https://github.com/copier-org/copier/security/advisories/GHSA-34mv-rjq9-5mch

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