UBUNTU-CVE-2026-65630

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Source
https://ubuntu.com/security/CVE-2026-65630
Import Source
https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-65630.json
JSON Data
https://api.osv.dev/v1/vulns/UBUNTU-CVE-2026-65630
Upstream
Published
2026-10-27T00:00:00Z
Modified
2026-10-28T01:07:39Z
Severity
  • 5.9 (Medium) CVSS_V4 - CVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N CVSS Calculator
  • Ubuntu - medium
Summary
[none]
Details

Observable Timing Discrepancy vulnerability in potatosalad jose allows recovery of a long-term X25519 private key through a timing side channel in the pure-Erlang Curve25519 fallback. The pure-Erlang X25519 implementation performs scalar multiplication over the secret private key using a recursive Montgomery ladder (jose_jwa_x25519:curve25519/2) whose clauses branch on individual bits of the clamped private scalar, and whose per-step operations (jose_jwa_x25519:montgomery_add/3 and jose_jwa_x25519:montgomery_double/1) and field inversion are built from value-dependent Erlang bignum arithmetic (multiplication, remainder, and modular exponentiation). Although the ladder is operation-count balanced and fixed at 254 steps, the concrete integer values processed at each step, and therefore the running time, depend on the secret scalar. The execution time of the public entry points jose_jwa_x25519:scalarmult/2, jose_jwa_x25519:x25519/2, jose_jwa_x25519:x25519_base/1, and jose_jwa_x25519:sk_to_pk/1 is thus a function of the private key. This path is reachable from the public API, most notably when a service decrypts attacker-supplied ECDH-ES (JWE) messages with a long-term X25519 key (for example through JOSE.JWK.box_decrypt_ecdh_es/2, which reaches jose_jwa_curve25519:x25519_shared_secret/2 and the ladder). An attacker who can submit ciphertexts and measure decryption timing can, in principle, recover the private key bit by bit, defeating the resistance X25519 was designed to provide. Recovery of the key compromises the confidentiality and authenticity of all data protected by it. This issue affects jose: from 1.10.0 before 1.11.13.

References

Affected packages

Ubuntu:18.04:LTS
jose

Package

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

Affected ranges

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

Affected versions

Other
10-2
10-2build1

Ecosystem specific 

{
    "binaries":  [
        {
            "binary_name":  "jose",
            "binary_version":  "10-2build1"
        },
        {
            "binary_name":  "libjose0",
            "binary_version":  "10-2build1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-65630.json"
Ubuntu:20.04:LTS
jose

Package

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

Affected ranges

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

Affected versions

Other
10-2build2

Ecosystem specific 

{
    "binaries":  [
        {
            "binary_name":  "jose",
            "binary_version":  "10-2build2"
        },
        {
            "binary_name":  "libjose0",
            "binary_version":  "10-2build2"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-65630.json"
Ubuntu:22.04:LTS
jose

Package

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

Affected ranges

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

Affected versions

Other
10-3
11-2

Ecosystem specific 

{
    "binaries":  [
        {
            "binary_name":  "jose",
            "binary_version":  "11-2"
        },
        {
            "binary_name":  "libjose0",
            "binary_version":  "11-2"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-65630.json"
Ubuntu:24.04:LTS
jose

Package

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

Affected ranges

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

Affected versions

Other
11-2
11-3
11-3build1
11-3build2
13-1

Ecosystem specific 

{
    "binaries":  [
        {
            "binary_name":  "jose",
            "binary_version":  "13-1"
        },
        {
            "binary_name":  "libjose0",
            "binary_version":  "13-1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-65630.json"
Ubuntu:26.04:LTS
jose

Package

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

Affected ranges

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

Affected versions

Other
14-2build1

Ecosystem specific 

{
    "binaries":  [
        {
            "binary_name":  "jose",
            "binary_version":  "14-2build1"
        },
        {
            "binary_name":  "libjose0",
            "binary_version":  "14-2build1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-65630.json"
Ubuntu:26.10
jose

Package

Name
jose
Purl
pkg:deb/ubuntu/jose?arch=source&distro=stonking

Affected ranges

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

Affected versions

Other
14-2build1
14-2build2

Ecosystem specific 

{
    "binaries":  [
        {
            "binary_name":  "jose",
            "binary_version":  "14-2build2"
        },
        {
            "binary_name":  "libjose0",
            "binary_version":  "14-2build2"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-65630.json"