High
calibre: Bypass of Python template restrictions via nested `template()` leading to RCE
Type: advisorySources: OSV
calibre is an e-book manager. Prior to 9.12.0, calibre processes attacker-controlled composite_template metadata from a malicious EPUB, OPF, PDF, or similar file through program: and a nested template() call whose formatter does not inherit allow_python_templates=False, allowing a nested python: template to reach compile_python_template and execute arbitrary Python code when the file is opened or imported. This issue is fixed in version 9.12.0.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2026-73248
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 3 Nov 2026, 15:31 UTC · Revision 1
Source evidence
calibre: Bypass of Python template restrictions via nested `template()` leading to RCE
core-osv · Original sourcePublished 11 Aug 2026, 21:56 UTC
calibre is an e-book manager. Prior to 9.12.0, calibre processes attacker-controlled composite_template metadata from a malicious EPUB, OPF, PDF, or similar file through program: and a nested template() call whose formatter does not inherit allow_python_templates=False, allowing a nested python: template to reach compile_python_template and execute arbitrary Python code when the file is opened or imported. This issue is fixed in version 9.12.0.
osv:CVE-2026-73248
Complete source record
{
"id": "7c4ac0b296f3b65195870da01753538d3964cf36fc9e91ac8785054cec371012",
"url": "https://osv.dev/vulnerability/CVE-2026-73248",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "calibre: Bypass of Python template restrictions via nested `template()` leading to RCE",
"summary": "calibre is an e-book manager. Prior to 9.12.0, calibre processes attacker-controlled composite_template metadata from a malicious EPUB, OPF, PDF, or similar file through program: and a nested template() call whose formatter does not inherit allow_python_templates=False, allowing a nested python: template to reach compile_python_template and execute arbitrary Python code when the file is opened or imported. This issue is fixed in version 9.12.0.",
"evidence": "osv:CVE-2026-73248",
"products": [],
"severity": "high",
"structured": {
"id": "CVE-2026-73248",
"aliases": [
"CVE-2026-73248",
"GHSA-4f7g-rjfp-hmvx"
],
"metrics": [
{
"type": "CVSS_V4",
"score": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N"
}
],
"affected": [
{
"ranges": [
{
"repo": "https://github.com/kovidgoyal/calibre",
"type": "GIT",
"events": [
{
"introduced": "0"
},
{
"fixed": "993dd952284ce4bb8199ddeef20643f94bb0b437"
},
{
"fixed": "dac9990458374a81a5372a768bba6527d965aac8"
}
],
"database_specific": {
"extracted_events": [
{
"range": [
{
"introduced": "0"
},
{
"fixed": "9.12.0"
}
],
"source": "AFFECTED_FIELD",
"strategy": "StringRangeExpression"
},
{
"range": [
{
"fixed": "dac9990458374a81a5372a768bba6527d965aac8"
}
],
"source": "REFERENCES_COMMIT"
},
{
"range": [
{
"fixed": "993dd952284ce4bb8199ddeef20643f94bb0b437"
}
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"source": "REFERENCES_TAG",
"original_tag": "v9.12.0"
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"database_specific": {
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}
}
],
"modified": "2026-10-28T02:30:29.921942035Z",
"provider": "osv",
"references": [
"https://github.com/kovidgoyal/calibre/releases/tag/v9.12.0",
"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/73xxx/CVE-2026-73248.json",
"https://github.com/kovidgoyal/calibre/security/advisories/GHSA-4f7g-rjfp-hmvx",
"https://nvd.nist.gov/vuln/detail/CVE-2026-73248",
"https://github.com/kovidgoyal/calibre/commit/dac9990458374a81a5372a768bba6527d965aac8"
],
"provider_metadata": {
"cwe_ids": [
"CWE-94",
"CWE-95"
],
"cna_assigner": "GitHub_M",
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/73xxx/CVE-2026-73248.json"
}
},
"related_cves": [
{
"value": "CVE-2026-73248",
"evidence": "/id"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 496847,
"published_at": "2026-08-11T21:56:08.569+00:00"
}