CVE-2026-53951

Copier is a library and CLI app for rendering project templates. In versions 9.5.0 through 9.15.1, the `trust` setting's prefix match (`copier/_settings.py`) compares the template URL against a trusted prefix with a raw `str.startswith` and no path normalization, while the URL is normalized when the template is actually fetched (`Path.resolve()` for local paths; libcurl dot-segment removal for `https`). A template reference that textually starts with a trusted prefix but contains `..` is therefore granted trust yet resolves to a different, attacker-controlled template, whose `tasks` / `migrations` / `jinja_extensions` then run without the `--trust` prompt — arbitrary command execution. Version 9.15.2 patches the issue.

CVSS

No CVSS.

References

Link	Resource
https://github.com/copier-org/copier/releases/tag/v9.15.2
https://github.com/copier-org/copier/security/advisories/GHSA-9gmc-jqmh-3rvm
https://github.com/copier-org/copier/security/advisories/GHSA-9gmc-jqmh-3rvm

Configurations

No configuration.

History

09 Jul 2026, 15:16

Type	Values Removed	Values Added
References	~~() https://github.com/copier-org/copier/security/advisories/GHSA-9gmc-jqmh-3rvm -~~	() https://github.com/copier-org/copier/security/advisories/GHSA-9gmc-jqmh-3rvm -

08 Jul 2026, 16:16

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-07-08 16:16

Updated : 2026-07-10 19:06

NVD link : CVE-2026-53951

Mitre link : CVE-2026-53951

CVE.ORG link : CVE-2026-53951

JSON object : View

Products Affected

No product.

CWE

CWE-22

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

CWE-94

Improper Control of Generation of Code ('Code Injection')

{"id": "CVE-2026-53951", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-53951", "role": "CISA Coordinator", "options": [{"exploitation": "poc"}, {"automatable": "no"}, {"technicalImpact": "total"}], "version": "2.0.3", "timestamp": "2026-07-09T13:46:41.622835Z"}}], "cvssMetricV40": [{"type": "Secondary", "source": "security-advisories@github.com", "cvssData": {"Safety": "NOT_DEFINED", "version": "4.0", "Recovery": "NOT_DEFINED", "baseScore": 8.8, "Automatable": "NOT_DEFINED", "attackVector": "LOCAL", "baseSeverity": "HIGH", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "exploitMaturity": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED", "userInteraction": "PASSIVE", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "privilegesRequired": "NONE", "subIntegrityImpact": "HIGH", "vulnIntegrityImpact": "HIGH", "integrityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "subAvailabilityImpact": "HIGH", "vulnAvailabilityImpact": "HIGH", "availabilityRequirement": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "subConfidentialityImpact": "HIGH", "vulnConfidentialityImpact": "HIGH", "confidentialityRequirement": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED"}}]}, "affected": [{"source": "security-advisories@github.com", "affectedData": [{"vendor": "copier-org", "product": "copier", "versions": [{"status": "affected", "version": ">= 9.5.0, < 9.15.2"}]}]}], "published": "2026-07-08T16:16:30.623", "references": [{"url": "https://github.com/copier-org/copier/releases/tag/v9.15.2", "source": "security-advisories@github.com"}, {"url": "https://github.com/copier-org/copier/security/advisories/GHSA-9gmc-jqmh-3rvm", "source": "security-advisories@github.com"}, {"url": "https://github.com/copier-org/copier/security/advisories/GHSA-9gmc-jqmh-3rvm", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"}], "vulnStatus": "Deferred", "weaknesses": [{"type": "Secondary", "source": "security-advisories@github.com", "description": [{"lang": "en", "value": "CWE-22"}, {"lang": "en", "value": "CWE-94"}]}], "descriptions": [{"lang": "en", "value": "Copier is a library and CLI app for rendering project templates. In versions 9.5.0 through 9.15.1, the `trust` setting's prefix match\n(`copier/_settings.py`) compares the template URL against a trusted prefix with a raw `str.startswith` and no path normalization, while the URL is normalized when the template is actually fetched (`Path.resolve()` for local paths; libcurl dot-segment removal for `https`). A template reference that textually starts with a trusted prefix but contains `..` is therefore granted trust yet resolves to a different, attacker-controlled template, whose `tasks` / `migrations` / `jinja_extensions` then run without the `--trust` prompt \u2014 arbitrary command execution. Version 9.15.2 patches the issue."}], "lastModified": "2026-07-10T19:06:45.623", "sourceIdentifier": "security-advisories@github.com"}