ubuntu-cve-2026-27448
Vulnerability from osv_ubuntu
Published
2026-03-18 00:00
Modified
2026-05-28 15:34
Summary
Details
pyOpenSSL is a Python wrapper around the OpenSSL library. Starting in version 0.14.0 and prior to version 26.0.0, if a user provided callback to set_tlsext_servername_callback raised an unhandled exception, this would result in a connection being accepted. If a user was relying on this callback for any security-sensitive behavior, this could allow bypassing it. Starting in version 26.0.0, unhandled exceptions now result in rejecting the connection.
Severity
5.3 (Medium)
N/A (UNKNOWN)
References
{
"affected": [
{
"ecosystem_specific": {
"availability": "Available with Ubuntu Pro with Legacy support add-on: https://ubuntu.com/pro",
"binaries": [
{
"binary_name": "python-openssl",
"binary_version": "0.15.1-2ubuntu0.2+esm1"
},
{
"binary_name": "python3-openssl",
"binary_version": "0.15.1-2ubuntu0.2+esm1"
}
],
"priority_reason": "This has been rated low severity by pyOpenSSL developers"
},
"package": {
"ecosystem": "Ubuntu:Pro:16.04:LTS",
"name": "pyopenssl",
"purl": "pkg:deb/ubuntu/pyopenssl@0.15.1-2ubuntu0.2+esm1?arch=source\u0026distro=esm-infra-legacy/xenial"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "0.15.1-2ubuntu0.2+esm1"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"0.15.1-2build1",
"0.15.1-2ubuntu0.2"
]
},
{
"ecosystem_specific": {
"availability": "Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro",
"binaries": [
{
"binary_name": "python-openssl",
"binary_version": "17.5.0-1ubuntu1+esm1"
},
{
"binary_name": "python3-openssl",
"binary_version": "17.5.0-1ubuntu1+esm1"
}
],
"priority_reason": "This has been rated low severity by pyOpenSSL developers"
},
"package": {
"ecosystem": "Ubuntu:Pro:18.04:LTS",
"name": "pyopenssl",
"purl": "pkg:deb/ubuntu/pyopenssl@17.5.0-1ubuntu1+esm1?arch=source\u0026distro=esm-infra/bionic"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "17.5.0-1ubuntu1+esm1"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"16.2.0-1",
"17.5.0-1",
"17.5.0-1ubuntu1"
]
},
{
"ecosystem_specific": {
"availability": "Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro",
"binaries": [
{
"binary_name": "python-openssl",
"binary_version": "19.0.0-1ubuntu0.1~esm1"
},
{
"binary_name": "python3-openssl",
"binary_version": "19.0.0-1ubuntu0.1~esm1"
}
],
"priority_reason": "This has been rated low severity by pyOpenSSL developers"
},
"package": {
"ecosystem": "Ubuntu:Pro:20.04:LTS",
"name": "pyopenssl",
"purl": "pkg:deb/ubuntu/pyopenssl@19.0.0-1ubuntu0.1~esm1?arch=source\u0026distro=esm-infra/focal"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "19.0.0-1ubuntu0.1~esm1"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"19.0.0-1",
"19.0.0-1build1"
]
},
{
"ecosystem_specific": {
"availability": "No subscription required",
"binaries": [
{
"binary_name": "python3-openssl",
"binary_version": "21.0.0-1ubuntu0.1"
}
],
"priority_reason": "This has been rated low severity by pyOpenSSL developers"
},
"package": {
"ecosystem": "Ubuntu:22.04:LTS",
"name": "pyopenssl",
"purl": "pkg:deb/ubuntu/pyopenssl@21.0.0-1ubuntu0.1?arch=source\u0026distro=jammy"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "21.0.0-1ubuntu0.1"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"20.0.1-1",
"21.0.0-1"
]
},
{
"ecosystem_specific": {
"availability": "No subscription required",
"binaries": [
{
"binary_name": "python3-openssl",
"binary_version": "23.2.0-1ubuntu0.1"
}
],
"priority_reason": "This has been rated low severity by pyOpenSSL developers"
},
"package": {
"ecosystem": "Ubuntu:24.04:LTS",
"name": "pyopenssl",
"purl": "pkg:deb/ubuntu/pyopenssl@23.2.0-1ubuntu0.1?arch=source\u0026distro=noble"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "23.2.0-1ubuntu0.1"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"23.0.0-1",
"23.2.0-1"
]
},
{
"ecosystem_specific": {
"availability": "No subscription required",
"binaries": [
{
"binary_name": "python3-openssl",
"binary_version": "25.0.0-1ubuntu0.1"
}
],
"priority_reason": "This has been rated low severity by pyOpenSSL developers"
},
"package": {
"ecosystem": "Ubuntu:25.10",
"name": "pyopenssl",
"purl": "pkg:deb/ubuntu/pyopenssl@25.0.0-1ubuntu0.1?arch=source\u0026distro=questing"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "25.0.0-1ubuntu0.1"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"25.0.0-1"
]
}
],
"aliases": [],
"details": "pyOpenSSL is a Python wrapper around the OpenSSL library. Starting in version 0.14.0 and prior to version 26.0.0, if a user provided callback to `set_tlsext_servername_callback` raised an unhandled exception, this would result in a connection being accepted. If a user was relying on this callback for any security-sensitive behavior, this could allow bypassing it. Starting in version 26.0.0, unhandled exceptions now result in rejecting the connection.",
"id": "UBUNTU-CVE-2026-27448",
"modified": "2026-05-28T15:34:52Z",
"published": "2026-03-18T00:00:00Z",
"references": [
{
"type": "REPORT",
"url": "https://ubuntu.com/security/CVE-2026-27448"
},
{
"type": "REPORT",
"url": "https://www.cve.org/CVERecord?id=CVE-2026-27448"
},
{
"type": "REPORT",
"url": "https://github.com/pyca/pyopenssl/security/advisories/GHSA-vp96-hxj8-p424"
},
{
"type": "ADVISORY",
"url": "https://ubuntu.com/security/notices/USN-8115-1"
},
{
"type": "ADVISORY",
"url": "https://ubuntu.com/security/notices/USN-8335-1"
}
],
"related": [
"USN-8115-1",
"USN-8335-1"
],
"schema_version": "1.7.0",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U",
"type": "CVSS_V4"
},
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N",
"type": "CVSS_V3"
},
{
"score": "low",
"type": "Ubuntu"
}
],
"upstream": [
"CVE-2026-27448"
]
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
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