DEBIAN-CVE-2026-45409
Internationalized Domain Names in Applications (IDNA) for Python provides support for Internationalized Domain Names in Applications (IDNA) and Unicode IDNA Compatibility Processing. In versions prior to 3.15, payloads such as `"\u0660" * N` or `"\u30fb" * N + "\u6f22"` utilize the `valid_contexto` function prior to length rejection, and for high values of `N` will take a long time to process. This is the same issue as CVE-2024-3651, however the original remediation in 2024 was not a complete fix. A specially crafted argument to the `idna.encode()` function could consume significant resources. This may lead to a denial-of-service. Starting in version 3.14, the function rejects long inputs as soon as practicable prior to any further processing to minimize resource consumption. In version 3.15, this approach was extended to lesser used alternate functions (i.e. per-label conversions and codec support). A workaround is available. Domain names cannot exceed 253 characters in length. If this length limit is enforced prior to passing the domain to the `idna.encode()` function, it should no longer consume significant resources. This is triggered by arbitrarily large inputs that would not occur in normal usage, but may be passed to the library assuming there is no preliminary input validation by the higher-level application.
DEBIAN-CVE-2026-45409
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: osv:DEBIAN-CVE-2026-45409
python-idna
Source reference: /affected/0/package/name
- Affected versions
- 3.10-1
Source reference:
/affected/0/versions3.10-1~exp1Source reference:
/affected/0/versions3.11-1Source reference:
/affected/0/versions3.11-1.1Source reference:
/affected/0/versions3.18-1Source reference:
/affected/0/versions3.19-1Source reference:
/affected/0/versions3.3-1Source reference:
/affected/0/versions3.3-1+deb12u1Source reference:
/affected/0/versions3.3-2Source reference:
/affected/0/versions3.6-1Source reference:
/affected/0/versions3.6-2Source reference:
/affected/0/versions3.6-2.1Source reference:
/affected/0/versions3.8-1Source reference:
/affected/0/versions3.8-2Source reference:
/affected/0/versions - Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
python-idna
Source reference: /affected/1/package/name
- Affected versions
- 3.10-1
Source reference:
/affected/1/versions - Fixed versions
- 3.10-1+deb13u1
Source reference:
/affected/1/ranges - Prerequisites
- Not stated in this record
python-idna
Source reference: /affected/2/package/name
- Affected versions
- 3.10-1
Source reference:
/affected/2/versions3.11-1Source reference:
/affected/2/versions - Fixed versions
- 3.11-1.1
Source reference:
/affected/2/ranges - Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "python-idna",
"purl": "pkg:deb/debian/python-idna?arch=source&distro=bookworm",
"ecosystem": "Debian:12"
},
"versions": [
"3.10-1",
"3.10-1~exp1",
"3.11-1",
"3.11-1.1",
"3.18-1",
"3.19-1",
"3.3-1",
"3.3-1+deb12u1",
"3.3-2",
"3.6-1",
"3.6-2",
"3.6-2.1",
"3.8-1",
"3.8-2"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-45409.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "3.10-1+deb13u1"
}
]
}
],
"package": {
"name": "python-idna",
"purl": "pkg:deb/debian/python-idna?arch=source&distro=trixie",
"ecosystem": "Debian:13"
},
"versions": [
"3.10-1"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-45409.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "3.11-1.1"
}
]
}
],
"package": {
"name": "python-idna",
"purl": "pkg:deb/debian/python-idna?arch=source&distro=forky",
"ecosystem": "Debian:14"
},
"versions": [
"3.10-1",
"3.11-1"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-45409.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
}
]Publisher severity
No explicit severity was provided.
- Event
- #57703 · Revision 1
- Added to Heist Feed
- Publisher date