UBUNTU-CVE-2026-63311

See a problem?
Please try reporting it to the source first.

Source

https://ubuntu.com/security/CVE-2026-63311

Import Source

https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-63311.json

JSON Data

https://api.osv.dev/v1/vulns/UBUNTU-CVE-2026-63311

Upstream

CVE-2026-63311

Published

2026-08-25T00:00:00Z

Modified

2026-08-27T11:01:20.012340824Z

Severity

6.9 (Medium) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:L CVSS Calculator
5.3 (Medium) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N CVSS Calculator
6.9 (Medium) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:L CVSS Calculator
5.3 (Medium) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N CVSS Calculator
Ubuntu - medium

Summary

[none]

Details

NLTK before 3.10.0 (affected versions <= 3.9.4) contains a server-side request forgery (SSRF) vulnerability in the validatenetworkurl() function in nltk/pathsec.py. The resolvehostname() helper catches OSError and ValueError during socket.getaddrinfo() and returns an empty list; when DNS resolution fails, the validation loop executes no IP checks and the function fails open, allowing urlopen() to proceed without validation. An attacker who can trigger DNS resolution failures or use DNS rebinding can bypass SSRF protections and reach restricted network resources, including cloud metadata endpoints (e.g., 169.254.169.254).

References

Affected packages

Ubuntu:Pro:14.04:LTS

nltk

Package

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

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0Unknown introduced version / All previous versions are affected

Affected versions

2.*

2.0~b9-0ubuntu4

2.0~b9-0ubuntu4.1~esm2

2.0~b9-0ubuntu4.1~esm4

2.0~b9-0ubuntu4.1~esm5

2.0~b9-0ubuntu4.1~esm6

Ecosystem specific

{
    "binaries": [
        {
            "binary_version": "2.0~b9-0ubuntu4.1~esm6",
            "binary_name": "python-nltk"
        }
    ]
}

Database specific

source

"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-63311.json"

Ubuntu:Pro:16.04:LTS

nltk

Package

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

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0Unknown introduced version / All previous versions are affected

Affected versions

3.*

3.0.4-1

3.0.5-1

3.1-1

3.1-1ubuntu0.1

3.1-1ubuntu0.1+esm1

3.1-1ubuntu0.1+esm2

3.1-1ubuntu0.1+esm3

3.1-1ubuntu0.1+esm4

Ecosystem specific

{
    "binaries": [
        {
            "binary_version": "3.1-1ubuntu0.1+esm4",
            "binary_name": "python-nltk"
        },
        {
            "binary_version": "3.1-1ubuntu0.1+esm4",
            "binary_name": "python3-nltk"
        }
    ]
}

Database specific

source

"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-63311.json"

Ubuntu:Pro:18.04:LTS

nltk

Package

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

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0Unknown introduced version / All previous versions are affected

Affected versions

3.*

3.2.4-1

3.2.5-1

3.2.5-1ubuntu0.1

3.2.5-1ubuntu0.1+esm1

3.2.5-1ubuntu0.1+esm2

3.2.5-1ubuntu0.1+esm3

3.2.5-1ubuntu0.1+esm4

Ecosystem specific

{
    "binaries": [
        {
            "binary_version": "3.2.5-1ubuntu0.1+esm4",
            "binary_name": "python-nltk"
        },
        {
            "binary_version": "3.2.5-1ubuntu0.1+esm4",
            "binary_name": "python3-nltk"
        }
    ]
}

Database specific

source

"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-63311.json"

Ubuntu:Pro:20.04:LTS

nltk

Package

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

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0Unknown introduced version / All previous versions are affected

Affected versions

3.*

3.4.5-1

3.4.5-2

3.4.5-2ubuntu0.1~esm1

3.4.5-2ubuntu0.1~esm2

3.4.5-2ubuntu0.1~esm3

3.4.5-2ubuntu0.1~esm4

Ecosystem specific

{
    "binaries": [
        {
            "binary_version": "3.4.5-2ubuntu0.1~esm4",
            "binary_name": "python3-nltk"
        }
    ]
}

Database specific

source

"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-63311.json"

Ubuntu:Pro:22.04:LTS

nltk

Package

Name: nltk
Purl: pkg:deb/ubuntu/nltk?arch=source&distro=esm-apps%2Fjammy

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0Unknown introduced version / All previous versions are affected

Affected versions

3.*

3.5-1

3.6.5-1

3.6.7-1

3.7-1

3.7-1ubuntu0.1~esm1

3.7-1ubuntu0.1~esm2

Ecosystem specific

{
    "binaries": [
        {
            "binary_version": "3.7-1ubuntu0.1~esm2",
            "binary_name": "python3-nltk"
        }
    ]
}

Database specific

source

"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-63311.json"

Ubuntu:Pro:24.04:LTS

nltk

Package

Name: nltk
Purl: pkg:deb/ubuntu/nltk?arch=source&distro=esm-apps%2Fnoble

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0Unknown introduced version / All previous versions are affected

Affected versions

3.*

3.8.1-1

3.8.1-1ubuntu0.1~esm1

3.8.1-1ubuntu0.1~esm2

Ecosystem specific

{
    "binaries": [
        {
            "binary_version": "3.8.1-1ubuntu0.1~esm2",
            "binary_name": "python3-nltk"
        }
    ]
}

Database specific

source

"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-63311.json"

Ubuntu:Pro:26.04:LTS

nltk

Package

Name: nltk
Purl: pkg:deb/ubuntu/nltk?arch=source&distro=esm-apps%2Fresolute

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0Unknown introduced version / All previous versions are affected

Affected versions

3.*

3.9.1-2

3.9.1-2build1

3.9.2-1

3.9.2-1ubuntu0.1~esm1

3.9.2-1ubuntu0.1~esm2

Ecosystem specific

{
    "binaries": [
        {
            "binary_version": "3.9.2-1ubuntu0.1~esm2",
            "binary_name": "python3-nltk"
        }
    ]
}

Database specific

source

"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-63311.json"