CVE-2026-23986 (GCVE-0-2026-23986)
Vulnerability from cvelistv5
Published
2026-01-21 22:20
Modified
2026-01-22 16:49
Severity ?
VLAI Severity ?
EPSS score ?
CWE
- CWE-61 - UNIX Symbolic Link (Symlink) Following
Summary
Copier is a library and CLI app for rendering project templates. Prior to version 9.11.2, Copier suggests that it's safe to generate a project from a safe template, i.e. one that doesn't use unsafe features like custom Jinja extensions which would require passing the `--UNSAFE,--trust` flag. As it turns out, a safe template can currently write to arbitrary directories outside the destination path by using directory a symlink along with `_preserve_symlinks: true` and a generated directory structure whose rendered path is inside the symlinked directory. This way, a malicious template author can create a template that overwrites arbitrary files (according to the user's write permissions), e.g., to cause havoc. Version 9.11.2 patches the issue.
References
| URL | Tags | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
|
|||||||||||
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| copier-org | copier |
Version: < 9.11.2 |
{
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2026-23986",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "no"
},
{
"Technical Impact": "total"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-01-22T15:10:50.987653Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-01-22T16:49:26.426Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"product": "copier",
"vendor": "copier-org",
"versions": [
{
"status": "affected",
"version": "\u003c 9.11.2"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "Copier is a library and CLI app for rendering project templates. Prior to version 9.11.2, Copier suggests that it\u0027s safe to generate a project from a safe template, i.e. one that doesn\u0027t use unsafe features like custom Jinja extensions which would require passing the `--UNSAFE,--trust` flag. As it turns out, a safe template can currently write to arbitrary directories outside the destination path by using directory a symlink along with `_preserve_symlinks: true` and a generated directory structure whose rendered path is inside the symlinked directory. This way, a malicious template author can create a template that overwrites arbitrary files (according to the user\u0027s write permissions), e.g., to cause havoc. Version 9.11.2 patches the issue."
}
],
"metrics": [
{
"cvssV4_0": {
"attackComplexity": "LOW",
"attackRequirements": "NONE",
"attackVector": "LOCAL",
"baseScore": 6.9,
"baseSeverity": "MEDIUM",
"privilegesRequired": "NONE",
"subAvailabilityImpact": "NONE",
"subConfidentialityImpact": "NONE",
"subIntegrityImpact": "NONE",
"userInteraction": "PASSIVE",
"vectorString": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N",
"version": "4.0",
"vulnAvailabilityImpact": "HIGH",
"vulnConfidentialityImpact": "NONE",
"vulnIntegrityImpact": "HIGH"
}
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-61",
"description": "CWE-61: UNIX Symbolic Link (Symlink) Following",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-01-21T22:20:37.720Z",
"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
"shortName": "GitHub_M"
},
"references": [
{
"name": "https://github.com/copier-org/copier/security/advisories/GHSA-4fqp-r85r-hxqh",
"tags": [
"x_refsource_CONFIRM"
],
"url": "https://github.com/copier-org/copier/security/advisories/GHSA-4fqp-r85r-hxqh"
},
{
"name": "https://github.com/copier-org/copier/commit/b3a7b3772d17cf0e7a4481978188c9f536c8d8f6",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/copier-org/copier/commit/b3a7b3772d17cf0e7a4481978188c9f536c8d8f6"
},
{
"name": "https://github.com/copier-org/copier/releases/tag/v9.11.2",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/copier-org/copier/releases/tag/v9.11.2"
}
],
"source": {
"advisory": "GHSA-4fqp-r85r-hxqh",
"discovery": "UNKNOWN"
},
"title": "Copier safe template has arbitrary filesystem write access via directory symlinks when _preserve_symlinks: true"
}
},
"cveMetadata": {
"assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
"assignerShortName": "GitHub_M",
"cveId": "CVE-2026-23986",
"datePublished": "2026-01-21T22:20:37.720Z",
"dateReserved": "2026-01-19T18:49:20.656Z",
"dateUpdated": "2026-01-22T16:49:26.426Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"vulnrichment": {
"containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-23986\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"no\"}, {\"Technical Impact\": \"total\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-01-22T15:10:50.987653Z\"}}}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-01-22T15:10:52.135Z\"}}], \"cna\": {\"title\": \"Copier safe template has arbitrary filesystem write access via directory symlinks when _preserve_symlinks: true\", \"source\": {\"advisory\": \"GHSA-4fqp-r85r-hxqh\", \"discovery\": \"UNKNOWN\"}, \"metrics\": [{\"cvssV4_0\": {\"version\": \"4.0\", \"baseScore\": 6.9, \"attackVector\": \"LOCAL\", \"baseSeverity\": \"MEDIUM\", \"vectorString\": \"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N\", \"userInteraction\": \"PASSIVE\", \"attackComplexity\": \"LOW\", \"attackRequirements\": \"NONE\", \"privilegesRequired\": \"NONE\", \"subIntegrityImpact\": \"NONE\", \"vulnIntegrityImpact\": \"HIGH\", \"subAvailabilityImpact\": \"NONE\", \"vulnAvailabilityImpact\": \"HIGH\", \"subConfidentialityImpact\": \"NONE\", \"vulnConfidentialityImpact\": \"NONE\"}}], \"affected\": [{\"vendor\": \"copier-org\", \"product\": \"copier\", \"versions\": [{\"status\": \"affected\", \"version\": \"\u003c 9.11.2\"}]}], \"references\": [{\"url\": \"https://github.com/copier-org/copier/security/advisories/GHSA-4fqp-r85r-hxqh\", \"name\": \"https://github.com/copier-org/copier/security/advisories/GHSA-4fqp-r85r-hxqh\", \"tags\": [\"x_refsource_CONFIRM\"]}, {\"url\": \"https://github.com/copier-org/copier/commit/b3a7b3772d17cf0e7a4481978188c9f536c8d8f6\", \"name\": \"https://github.com/copier-org/copier/commit/b3a7b3772d17cf0e7a4481978188c9f536c8d8f6\", \"tags\": [\"x_refsource_MISC\"]}, {\"url\": \"https://github.com/copier-org/copier/releases/tag/v9.11.2\", \"name\": \"https://github.com/copier-org/copier/releases/tag/v9.11.2\", \"tags\": [\"x_refsource_MISC\"]}], \"descriptions\": [{\"lang\": \"en\", \"value\": \"Copier is a library and CLI app for rendering project templates. Prior to version 9.11.2, Copier suggests that it\u0027s safe to generate a project from a safe template, i.e. one that doesn\u0027t use unsafe features like custom Jinja extensions which would require passing the `--UNSAFE,--trust` flag. As it turns out, a safe template can currently write to arbitrary directories outside the destination path by using directory a symlink along with `_preserve_symlinks: true` and a generated directory structure whose rendered path is inside the symlinked directory. This way, a malicious template author can create a template that overwrites arbitrary files (according to the user\u0027s write permissions), e.g., to cause havoc. Version 9.11.2 patches the issue.\"}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-61\", \"description\": \"CWE-61: UNIX Symbolic Link (Symlink) Following\"}]}], \"providerMetadata\": {\"orgId\": \"a0819718-46f1-4df5-94e2-005712e83aaa\", \"shortName\": \"GitHub_M\", \"dateUpdated\": \"2026-01-21T22:20:37.720Z\"}}}",
"cveMetadata": "{\"cveId\": \"CVE-2026-23986\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-01-22T16:49:26.426Z\", \"dateReserved\": \"2026-01-19T18:49:20.656Z\", \"assignerOrgId\": \"a0819718-46f1-4df5-94e2-005712e83aaa\", \"datePublished\": \"2026-01-21T22:20:37.720Z\", \"assignerShortName\": \"GitHub_M\"}",
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
}
}
Loading…
Loading…
Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
Loading…
Loading…