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
  • CVE-2026-34876
Published
2026-04-02T16:16:00Z
Modified
2026-04-13T12:53:52.073797Z
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 mbedtlsccmfinish() in library/ccm.c allows attackers to obtain adjacent CCM context data via invocation of the multipart CCM API with an oversized taglen parameter. This is caused by missing validation of the taglen 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 mbedtlsccmfinish() 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@2.2.1-2ubuntu0.3?arch=source&distro=xenial

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown 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_version": "2.2.1-2ubuntu0.3",
            "binary_name": "libmbedcrypto0"
        },
        {
            "binary_version": "2.2.1-2ubuntu0.3",
            "binary_name": "libmbedtls-dev"
        },
        {
            "binary_version": "2.2.1-2ubuntu0.3",
            "binary_name": "libmbedtls10"
        },
        {
            "binary_version": "2.2.1-2ubuntu0.3",
            "binary_name": "libmbedx509-0"
        }
    ]
}

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@3.6.2-3ubuntu1?arch=source&distro=questing

Affected ranges

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

Affected versions

3.*
3.6.2-3ubuntu1

Ecosystem specific 

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

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@2.8.0-1ubuntu0.1~esm1?arch=source&distro=esm-apps/bionic

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown 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_version": "2.8.0-1ubuntu0.1~esm1",
            "binary_name": "libmbedcrypto1"
        },
        {
            "binary_version": "2.8.0-1ubuntu0.1~esm1",
            "binary_name": "libmbedtls-dev"
        },
        {
            "binary_version": "2.8.0-1ubuntu0.1~esm1",
            "binary_name": "libmbedtls10"
        },
        {
            "binary_version": "2.8.0-1ubuntu0.1~esm1",
            "binary_name": "libmbedx509-0"
        }
    ]
}

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@2.16.4-1ubuntu2+esm1?arch=source&distro=esm-apps/focal

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown 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_version": "2.16.4-1ubuntu2+esm1",
            "binary_name": "libmbedcrypto3"
        },
        {
            "binary_version": "2.16.4-1ubuntu2+esm1",
            "binary_name": "libmbedtls-dev"
        },
        {
            "binary_version": "2.16.4-1ubuntu2+esm1",
            "binary_name": "libmbedtls12"
        },
        {
            "binary_version": "2.16.4-1ubuntu2+esm1",
            "binary_name": "libmbedx509-0"
        }
    ]
}

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@2.28.0-1ubuntu0.1~esm1?arch=source&distro=esm-apps/jammy

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown 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_version": "2.28.0-1ubuntu0.1~esm1",
            "binary_name": "libmbedcrypto7"
        },
        {
            "binary_version": "2.28.0-1ubuntu0.1~esm1",
            "binary_name": "libmbedtls-dev"
        },
        {
            "binary_version": "2.28.0-1ubuntu0.1~esm1",
            "binary_name": "libmbedtls14"
        },
        {
            "binary_version": "2.28.0-1ubuntu0.1~esm1",
            "binary_name": "libmbedx509-1"
        }
    ]
}

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@2.28.8-1ubuntu0.1~esm1?arch=source&distro=esm-apps/noble

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown 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_version": "2.28.8-1ubuntu0.1~esm1",
            "binary_name": "libmbedcrypto7t64"
        },
        {
            "binary_version": "2.28.8-1ubuntu0.1~esm1",
            "binary_name": "libmbedtls-dev"
        },
        {
            "binary_version": "2.28.8-1ubuntu0.1~esm1",
            "binary_name": "libmbedtls14t64"
        },
        {
            "binary_version": "2.28.8-1ubuntu0.1~esm1",
            "binary_name": "libmbedx509-1t64"
        }
    ]
}

Database specific

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