UBUNTU-CVE-2026-6291

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Source
https://ubuntu.com/security/CVE-2026-6291
Import Source
https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-6291.json
JSON Data
https://api.osv.dev/v1/vulns/UBUNTU-CVE-2026-6291
Upstream
  • CVE-2026-6291
Published
2026-06-25T18:16:00Z
Modified
2026-06-29T23:19:16.617229810Z
Severity
  • 6.0 (Medium) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N CVSS Calculator
  • 6.5 (Medium) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N CVSS Calculator
  • Ubuntu - medium
Summary
[none]
Details

Bleichenbacher padding oracle in PKCS#7 KTRI decryption. When decrypting PKCS#7 EnvelopedData using RSA PKCS#1 v1.5 key transport, wolfSSL returned distinguishable error codes depending on whether RSA padding validation failed versus whether the decrypted content was malformed. An attacker able to submit crafted EnvelopedData messages and observe error responses could use this as a padding oracle to incrementally recover the encrypted Content Encryption Key (CEK). The fix generates a deterministic pseudo-random fake CEK on padding failure (via HMAC-SHA256) and proceeds with decryption identically, using constant-time operations throughout, so that all failure paths produce the same error regardless of padding validity.

References

Affected packages

Ubuntu:16.04:LTS
wolfssl

Package

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

Affected ranges

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

Affected versions

3.*
3.4.8+dfsg-1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libcyassl5",
            "binary_version": "3.4.8+dfsg-1"
        },
        {
            "binary_name": "libwolfssl0",
            "binary_version": "3.4.8+dfsg-1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-6291.json"
Ubuntu:18.04:LTS
wolfssl

Package

Name
wolfssl
Purl
pkg:deb/ubuntu/wolfssl?arch=source&distro=bionic

Affected ranges

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

Affected versions

3.*
3.10.2+dfsg-2
3.12.0+dfsg-1
3.12.2+dfsg-1
3.13.0+dfsg-1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libwolfssl15",
            "binary_version": "3.13.0+dfsg-1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-6291.json"
Ubuntu:20.04:LTS
wolfssl

Package

Name
wolfssl
Purl
pkg:deb/ubuntu/wolfssl?arch=source&distro=focal

Affected ranges

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

Affected versions

4.*
4.1.0+dfsg-2
4.2.0+dfsg-1
4.2.0+dfsg-2
4.2.0+dfsg-3
4.3.0+dfsg-2

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libwolfssl24",
            "binary_version": "4.3.0+dfsg-2"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-6291.json"
Ubuntu:22.04:LTS
wolfssl

Package

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

Affected ranges

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

Affected versions

4.*
4.6.0-3
5.*
5.0.0-1
5.1.1-1
5.2.0-1
5.2.0-2

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libwolfssl32",
            "binary_version": "5.2.0-2"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-6291.json"
Ubuntu:24.04:LTS
wolfssl

Package

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

Affected ranges

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

Affected versions

5.*
5.5.4-2
5.5.4-2.1
5.6.4-2
5.6.6-1.2
5.6.6-1.3
5.6.6-1.3build1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libwolfssl42t64",
            "binary_version": "5.6.6-1.3build1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-6291.json"
Ubuntu:25.10
wolfssl

Package

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

Affected ranges

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

Affected versions

5.*
5.7.2-0.1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libwolfssl42t64",
            "binary_version": "5.7.2-0.1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-6291.json"
Ubuntu:26.04:LTS
wolfssl

Package

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

Affected ranges

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

Affected versions

5.*
5.7.2-0.1
5.8.2-1.2
5.8.4-1
5.9.1-0.1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libwolfssl44",
            "binary_version": "5.9.1-0.1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-6291.json"