UBUNTU-CVE-2026-33630
c-ares is an asynchronous resolver library. From ver 1.32.3 until 1.34.7, a use-after-free / double-free in c-ares' query-completion handling. The same flaw — a query's callback being invoked while the query is still linked in the channel's internal lookup structures — is present at multiple points in the resend/finish path (timeout handling, response handling, and query dispatch). If the query, or for ares_getaddrinfo() the owning host_query, is freed as a side effect of that callback, it is then accessed and/or freed a second time. This vulnerability is fixed in ver 1.34.7.
UBUNTU-CVE-2026-33630
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:UBUNTU-CVE-2026-33630
c-ares
Source reference: /affected/0/package/name
- Affected versions
- 1.34.4-2.1
Source reference:
/affected/0/versions1.34.5-1Source reference:
/affected/0/versions1.34.5-1ubuntu0.1Source reference:
/affected/0/versions - Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
c-ares
Source reference: /affected/1/package/name
- Affected versions
- 1.34.5-1
Source reference:
/affected/1/versions1.34.6-1Source reference:
/affected/1/versions - Fixed versions
- 1.34.6-1ubuntu0.1
Source reference:
/affected/1/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": "c-ares",
"purl": "pkg:deb/ubuntu/c-ares?arch=source&distro=questing",
"ecosystem": "Ubuntu:25.10"
},
"versions": [
"1.34.4-2.1",
"1.34.5-1",
"1.34.5-1ubuntu0.1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33630.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libc-ares2",
"binary_version": "1.34.5-1ubuntu0.1"
},
{
"binary_name": "libcares2",
"binary_version": "1.34.5-1ubuntu0.1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "1.34.6-1ubuntu0.1"
}
]
}
],
"package": {
"name": "c-ares",
"purl": "pkg:deb/ubuntu/c-ares?arch=source&distro=resolute",
"ecosystem": "Ubuntu:26.04:LTS"
},
"versions": [
"1.34.5-1",
"1.34.6-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33630.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libc-ares2",
"binary_version": "1.34.6-1ubuntu0.1"
},
{
"binary_name": "libcares2",
"binary_version": "1.34.6-1ubuntu0.1"
}
],
"availability": "No subscription required"
}
}
]Publisher severity
No explicit severity was provided.
- Event
- #33245 · Revision 1
- Added to Heist Feed
- Publisher date