UBUNTU-CVE-2026-63387

See a problem?
Please try reporting it to the source first.
Source
https://ubuntu.com/security/CVE-2026-63387
Import Source
https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-63387.json
JSON Data
https://api.osv.dev/v1/vulns/UBUNTU-CVE-2026-63387
Upstream
Published
2026-08-20T18:16:00Z
Modified
2026-09-02T19:36:26Z
Severity
  • 7.0 (High) CVSS_V3 - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H CVSS Calculator
  • Ubuntu - medium
Summary
[none]
Details

Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent has an off-by-one stack buffer overflow in evdns.c when dnsname_to_labels formats a name-bearing DNS record at the end of the 64 KB stack buffer allocated by evdns_server_request_format_response. The final-label check permits j plus label_len plus one to equal buf_len, after which the terminating null byte is written to buf[buf_len]. A crafted DNS server response containing PTR, CNAME, MX, NS, or SOA data can trigger the one-byte out-of-bounds write and crash or corrupt the process. This issue is fixed in versions 2.1.13 and 2.2.2-alpha.

References

Affected packages

Ubuntu:22.04:LTS
libevent

Package

Name
libevent
Purl
pkg:deb/ubuntu/libevent?arch=source&distro=jammy

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

2.*
2.1.12-stable-1
2.1.12-stable-1build1
2.1.12-stable-1build2
2.1.12-stable-1build3
2.1.12-stable-1ubuntu0.1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libevent-2.1-7",
            "binary_version": "2.1.12-stable-1ubuntu0.1"
        },
        {
            "binary_name": "libevent-core-2.1-7",
            "binary_version": "2.1.12-stable-1ubuntu0.1"
        },
        {
            "binary_name": "libevent-extra-2.1-7",
            "binary_version": "2.1.12-stable-1ubuntu0.1"
        },
        {
            "binary_name": "libevent-openssl-2.1-7",
            "binary_version": "2.1.12-stable-1ubuntu0.1"
        },
        {
            "binary_name": "libevent-pthreads-2.1-7",
            "binary_version": "2.1.12-stable-1ubuntu0.1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-63387.json"
Ubuntu:24.04:LTS
libevent

Package

Name
libevent
Purl
pkg:deb/ubuntu/libevent?arch=source&distro=noble

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

2.*
2.1.12-stable-9
2.1.12-stable-9ubuntu2
2.1.12-stable-9ubuntu2.1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libevent-2.1-7t64",
            "binary_version": "2.1.12-stable-9ubuntu2.1"
        },
        {
            "binary_name": "libevent-core-2.1-7t64",
            "binary_version": "2.1.12-stable-9ubuntu2.1"
        },
        {
            "binary_name": "libevent-extra-2.1-7t64",
            "binary_version": "2.1.12-stable-9ubuntu2.1"
        },
        {
            "binary_name": "libevent-openssl-2.1-7t64",
            "binary_version": "2.1.12-stable-9ubuntu2.1"
        },
        {
            "binary_name": "libevent-pthreads-2.1-7t64",
            "binary_version": "2.1.12-stable-9ubuntu2.1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-63387.json"
Ubuntu:26.04:LTS
libevent

Package

Name
libevent
Purl
pkg:deb/ubuntu/libevent?arch=source&distro=resolute

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

2.*
2.1.12-stable-10build1
2.1.12-stable-10build2
2.1.12-stable-10ubuntu0.1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libevent-2.1-7t64",
            "binary_version": "2.1.12-stable-10ubuntu0.1"
        },
        {
            "binary_name": "libevent-core-2.1-7t64",
            "binary_version": "2.1.12-stable-10ubuntu0.1"
        },
        {
            "binary_name": "libevent-extra-2.1-7t64",
            "binary_version": "2.1.12-stable-10ubuntu0.1"
        },
        {
            "binary_name": "libevent-openssl-2.1-7t64",
            "binary_version": "2.1.12-stable-10ubuntu0.1"
        },
        {
            "binary_name": "libevent-pthreads-2.1-7t64",
            "binary_version": "2.1.12-stable-10ubuntu0.1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-63387.json"
Ubuntu:Pro:14.04:LTS
libevent

Package

Name
libevent
Purl
pkg:deb/ubuntu/libevent?arch=source&distro=esm-infra-legacy%2Ftrusty

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

2.*
2.0.21-stable-1
2.0.21-stable-1ubuntu1
2.0.21-stable-1ubuntu1.14.04.1
2.0.21-stable-1ubuntu1.14.04.2
2.0.21-stable-1ubuntu1.14.04.2+esm1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libevent-2.0-5",
            "binary_version": "2.0.21-stable-1ubuntu1.14.04.2+esm1"
        },
        {
            "binary_name": "libevent-core-2.0-5",
            "binary_version": "2.0.21-stable-1ubuntu1.14.04.2+esm1"
        },
        {
            "binary_name": "libevent-extra-2.0-5",
            "binary_version": "2.0.21-stable-1ubuntu1.14.04.2+esm1"
        },
        {
            "binary_name": "libevent-openssl-2.0-5",
            "binary_version": "2.0.21-stable-1ubuntu1.14.04.2+esm1"
        },
        {
            "binary_name": "libevent-pthreads-2.0-5",
            "binary_version": "2.0.21-stable-1ubuntu1.14.04.2+esm1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-63387.json"
Ubuntu:Pro:16.04:LTS
libevent

Package

Name
libevent
Purl
pkg:deb/ubuntu/libevent?arch=source&distro=esm-infra-legacy%2Fxenial

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

2.*
2.0.21-stable-2
2.0.21-stable-2ubuntu0.16.04.1
2.0.21-stable-2ubuntu0.16.04.1+esm1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libevent-2.0-5",
            "binary_version": "2.0.21-stable-2ubuntu0.16.04.1+esm1"
        },
        {
            "binary_name": "libevent-core-2.0-5",
            "binary_version": "2.0.21-stable-2ubuntu0.16.04.1+esm1"
        },
        {
            "binary_name": "libevent-extra-2.0-5",
            "binary_version": "2.0.21-stable-2ubuntu0.16.04.1+esm1"
        },
        {
            "binary_name": "libevent-openssl-2.0-5",
            "binary_version": "2.0.21-stable-2ubuntu0.16.04.1+esm1"
        },
        {
            "binary_name": "libevent-pthreads-2.0-5",
            "binary_version": "2.0.21-stable-2ubuntu0.16.04.1+esm1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-63387.json"
Ubuntu:Pro:18.04:LTS
libevent

Package

Name
libevent
Purl
pkg:deb/ubuntu/libevent?arch=source&distro=esm-infra%2Fbionic

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

2.*
2.1.8-stable-4
2.1.8-stable-4build1
2.1.8-stable-4ubuntu0.1~esm1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libevent-2.1-6",
            "binary_version": "2.1.8-stable-4ubuntu0.1~esm1"
        },
        {
            "binary_name": "libevent-core-2.1-6",
            "binary_version": "2.1.8-stable-4ubuntu0.1~esm1"
        },
        {
            "binary_name": "libevent-extra-2.1-6",
            "binary_version": "2.1.8-stable-4ubuntu0.1~esm1"
        },
        {
            "binary_name": "libevent-openssl-2.1-6",
            "binary_version": "2.1.8-stable-4ubuntu0.1~esm1"
        },
        {
            "binary_name": "libevent-pthreads-2.1-6",
            "binary_version": "2.1.8-stable-4ubuntu0.1~esm1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-63387.json"
Ubuntu:Pro:20.04:LTS
libevent

Package

Name
libevent
Purl
pkg:deb/ubuntu/libevent?arch=source&distro=esm-infra%2Ffocal

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

2.*
2.1.8-stable-4build1
2.1.11-stable-1~exp0
2.1.11-stable-1
2.1.11-stable-1ubuntu0.1~esm1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libevent-2.1-7",
            "binary_version": "2.1.11-stable-1ubuntu0.1~esm1"
        },
        {
            "binary_name": "libevent-core-2.1-7",
            "binary_version": "2.1.11-stable-1ubuntu0.1~esm1"
        },
        {
            "binary_name": "libevent-extra-2.1-7",
            "binary_version": "2.1.11-stable-1ubuntu0.1~esm1"
        },
        {
            "binary_name": "libevent-openssl-2.1-7",
            "binary_version": "2.1.11-stable-1ubuntu0.1~esm1"
        },
        {
            "binary_name": "libevent-pthreads-2.1-7",
            "binary_version": "2.1.11-stable-1ubuntu0.1~esm1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-63387.json"