curl — security advisory
A double free vulnerability exists in libcurl <8.0.0 when sharing HSTS data between separate "handles". This sharing was introduced without considerations for do this sharing across separate threads but there was no indication of this fact in the documentation. Due to missing mutexes or thread locks, two threads sharing the same HSTS data could end up doing a double-free or use-after-free.
- Products
- curl
- Affected versions
- Not specified
- Fixed versions
- 7.88.1-7
- CVEs
- CVE-2023-27537
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 1 Nov 2026, 04:07 UTC · Revision 1
Source evidence
A double free vulnerability exists in libcurl <8.0.0 when sharing HSTS data between separate "handles". This sharing was introduced without considerations for do this sharing across separate threads but there was no indication of this fact in the documentation. Due to missing mutexes or thread locks, two threads sharing the same HSTS data could end up doing a double-free or use-after-free.
osv:DEBIAN-CVE-2023-27537
curl
Fixed versions: 7.88.1-7
curl
Fixed versions: 7.88.1-7
curl
Fixed versions: 7.88.1-7
Complete source record
{
"id": "4f7cd3a59c73910afc2f6f1a4b0bb6c6ff9233376c53cf1d4e99e6e775b2ed93",
"url": "https://osv.dev/vulnerability/DEBIAN-CVE-2023-27537",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "DEBIAN-CVE-2023-27537",
"summary": "A double free vulnerability exists in libcurl <8.0.0 when sharing HSTS data between separate \"handles\". This sharing was introduced without considerations for do this sharing across separate threads but there was no indication of this fact in the documentation. Due to missing mutexes or thread locks, two threads sharing the same HSTS data could end up doing a double-free or use-after-free.",
"evidence": "osv:DEBIAN-CVE-2023-27537",
"products": [
{
"name": {
"value": "curl",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
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"evidence": "/affected/0/ranges"
}
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"affected_versions": []
},
{
"name": {
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"severity": "medium",
"structured": {
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"aliases": [
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"metrics": [
{
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"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H"
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"affected": [
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"package": {
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"ecosystem": "Debian:12"
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"package": {
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"package": {
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"purl": "pkg:deb/debian/curl?arch=source&distro=forky",
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"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2023-27537.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
}
],
"modified": "2026-10-24T09:47:31.461503734Z",
"provider": "osv",
"upstream": [
"CVE-2023-27537"
],
"references": [
"https://security-tracker.debian.org/tracker/CVE-2023-27537"
]
},
"related_cves": [
{
"value": "CVE-2023-27537",
"evidence": "/upstream"
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],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 429003,
"published_at": "2023-03-30T20:15:07.617+00:00"
}