UBUNTU-CVE-2026-34876

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Source
https://ubuntu.com/security/CVE-2026-34876
Import Source
https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-34876.json
JSON Data
https://api.osv.dev/v1/vulns/UBUNTU-CVE-2026-34876
Upstream
Published
2026-04-02T16:16:00Z
Modified
2026-05-20T16:25:34Z
Severity
  • 7.5 (High) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N CVSS Calculator
  • Ubuntu - medium
Summary
[none]
Details

An issue was discovered in Mbed TLS 3.x before 3.6.6. An out-of-bounds read vulnerability in mbedtls_ccm_finish() in library/ccm.c allows attackers to obtain adjacent CCM context data via invocation of the multipart CCM API with an oversized tag_len parameter. This is caused by missing validation of the tag_len parameter against the size of the internal 16-byte authentication buffer. The issue affects the public multipart CCM API in Mbed TLS 3.x, where mbedtls_ccm_finish() can be invoked directly by applications. In Mbed TLS 4.x versions prior to the fix, the same missing validation exists in the internal implementation; however, the function is not exposed as part of the public API. Exploitation requires application-level invocation of the multipart CCM API.

References

Affected packages

Ubuntu:16.04:LTS
mbedtls

Package

Name
mbedtls
Purl
pkg:deb/ubuntu/mbedtls?arch=source&distro=xenial

Affected ranges

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

Affected versions

2.*
2.1.2-1
2.2.0-1
2.2.1-1
2.2.1-2
2.2.1-2ubuntu0.1
2.2.1-2ubuntu0.2
2.2.1-2ubuntu0.3

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libmbedcrypto0",
            "binary_version": "2.2.1-2ubuntu0.3"
        },
        {
            "binary_name": "libmbedtls10",
            "binary_version": "2.2.1-2ubuntu0.3"
        },
        {
            "binary_name": "libmbedx509-0",
            "binary_version": "2.2.1-2ubuntu0.3"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-34876.json"
Ubuntu:25.10
mbedtls

Package

Name
mbedtls
Purl
pkg:deb/ubuntu/mbedtls?arch=source&distro=questing

Affected ranges

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

Affected versions

3.*
3.6.2-3ubuntu1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libmbedcrypto16",
            "binary_version": "3.6.2-3ubuntu1"
        },
        {
            "binary_name": "libmbedtls21",
            "binary_version": "3.6.2-3ubuntu1"
        },
        {
            "binary_name": "libmbedx509-7",
            "binary_version": "3.6.2-3ubuntu1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-34876.json"
Ubuntu:26.04:LTS
mbedtls

Package

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

Affected ranges

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

Affected versions

3.*
3.6.2-3ubuntu1
3.6.5-0.1ubuntu1
3.6.5-0.1ubuntu2

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libmbedcrypto16",
            "binary_version": "3.6.5-0.1ubuntu2"
        },
        {
            "binary_name": "libmbedtls21",
            "binary_version": "3.6.5-0.1ubuntu2"
        },
        {
            "binary_name": "libmbedx509-7",
            "binary_version": "3.6.5-0.1ubuntu2"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-34876.json"
Ubuntu:Pro:18.04:LTS
mbedtls

Package

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

Affected ranges

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

Affected versions

2.*
2.5.1-1ubuntu1
2.6.0-1
2.7.0-2
2.8.0-1
2.8.0-1ubuntu0.1~esm1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libmbedcrypto1",
            "binary_version": "2.8.0-1ubuntu0.1~esm1"
        },
        {
            "binary_name": "libmbedtls10",
            "binary_version": "2.8.0-1ubuntu0.1~esm1"
        },
        {
            "binary_name": "libmbedx509-0",
            "binary_version": "2.8.0-1ubuntu0.1~esm1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-34876.json"
Ubuntu:Pro:20.04:LTS
mbedtls

Package

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

Affected ranges

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

Affected versions

2.*
2.16.2-1
2.16.3-1
2.16.4-1ubuntu2
2.16.4-1ubuntu2+esm1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libmbedcrypto3",
            "binary_version": "2.16.4-1ubuntu2+esm1"
        },
        {
            "binary_name": "libmbedtls12",
            "binary_version": "2.16.4-1ubuntu2+esm1"
        },
        {
            "binary_name": "libmbedx509-0",
            "binary_version": "2.16.4-1ubuntu2+esm1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-34876.json"
Ubuntu:Pro:22.04:LTS
mbedtls

Package

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

Affected ranges

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

Affected versions

2.*
2.16.9-0.1ubuntu1
2.16.11-0.1ubuntu1
2.16.11-0.3
2.28.0-1
2.28.0-1build1
2.28.0-1ubuntu0.1~esm1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libmbedcrypto7",
            "binary_version": "2.28.0-1ubuntu0.1~esm1"
        },
        {
            "binary_name": "libmbedtls14",
            "binary_version": "2.28.0-1ubuntu0.1~esm1"
        },
        {
            "binary_name": "libmbedx509-1",
            "binary_version": "2.28.0-1ubuntu0.1~esm1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-34876.json"
Ubuntu:Pro:24.04:LTS
mbedtls

Package

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

Affected ranges

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

Affected versions

2.*
2.28.3-1
2.28.6-1ubuntu1
2.28.7-1ubuntu1
2.28.7-1.1ubuntu1
2.28.8-1
2.28.8-1ubuntu0.1~esm1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libmbedcrypto7t64",
            "binary_version": "2.28.8-1ubuntu0.1~esm1"
        },
        {
            "binary_name": "libmbedtls14t64",
            "binary_version": "2.28.8-1ubuntu0.1~esm1"
        },
        {
            "binary_name": "libmbedx509-1t64",
            "binary_version": "2.28.8-1ubuntu0.1~esm1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-34876.json"