Vulnerability-Lookup

CVE-2026-53939 (GCVE-0-2026-53939)

Vulnerability from cvelistv5 – Published: 2026-09-08 23:36 – Updated: 2026-09-09 15:12

Title

OpenIDC/cjose uses all-zero Content Encryption Key for AES-CBC-HMAC JWE encryption

Summary

OpenIDC/cjose is a C library implementing the Javascript Object Signing and Encryption (JOSE). In versions 0.6.1 through 0.6.2.5, when cjose encrypts a JWE using an AES-CBC-HMAC content-encryption algorithm (`A128CBC-HS256`, `A192CBC-HS384`, or `A256CBC-HS512`) together with any key-management algorithm that generates a fresh content-encryption key (CEK), the CEK is all zero bytes instead of being randomly generated. The resulting JWE is therefore encrypted and authenticated under a fixed, publicly known key, so anyone who obtains the JWE can recover the plaintext and forge or modify the content. This is fixed in version 0.6.2.6 by `_cjose_jwe_set_cek_aes_cbc()` generating the CEK from `RAND_bytes`. A regression test asserts that the `encrypted_key` differs across two encryptions for each AES-CBC-HMAC variant. Until upgrading, for data encrypted with cjose, three options are available. Use an AES-GCM `enc` (`A128GCM` / `A192GCM` / `A256GCM`) instead of an AES-CBC-HMAC `enc`, use `alg=dir` with a caller-supplied CEK, or avoid using cjose for JWE encryption with the affected algorithm pair. These are mitigations for new ciphertexts only; data already encrypted under the zero key remains compromised and should be re-encrypted (and any secrets it contained rotated).

Severity

9.1 (Critical)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

SSVC

Exploitation: poc Automatable: yes Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-09 15:12 UTC

CWE

CWE-321 - Use of Hard-coded Cryptographic Key
CWE-330 - Use of Insufficiently Random Values

Assigner

GitHub_M mitre root

References

3 references

URL	Tags
https://github.com/OpenIDC/cjose/security/advisor…	x_refsource_CONFIRM
https://github.com/OpenIDC/cjose/commit/2a6e5bd96…	x_refsource_MISC
https://github.com/OpenIDC/cjose/releases/tag/v0.6.2.6	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version	CPE status
OpenIDC	cjose	Affected: >= 0.6.1, < 0.6.2.6	guessed

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-53939

Vulnerability from fkie_nvd - Published: 2026-09-09 00:17 - Updated: 2026-09-10 19:57

Severity

9.1 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/OpenIDC/cjose/commit/2a6e5bd969fa20059fb00913fb9f57d77ea6a4d9
	security-advisories@github.com	https://github.com/OpenIDC/cjose/releases/tag/v0.6.2.6
	security-advisories@github.com	https://github.com/OpenIDC/cjose/security/advisories/GHSA-f6wf-pqg3-6wqq
	134c704f-9b21-4f2e-91b3-4a467353bcc0	https://github.com/OpenIDC/cjose/security/advisories/GHSA-f6wf-pqg3-6wqq

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
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      "affectedData": [
        {
          "product": "cjose",
          "vendor": "OpenIDC",
          "versions": [
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    }
  ],
  "id": "CVE-2026-53939",
  "lastModified": "2026-09-10T19:57:48.533",
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          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
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          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N",
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          "lang": "en",
          "value": "CWE-330"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}

OPENSUSE-SU-2026:11784-1

Vulnerability from csaf_opensuse - Published: 2026-09-15 00:00 - Updated: 2026-09-17 17:24

Summary

libcjose-devel-0.6.2.8-2.1 on GA media

Severity

Moderate

Scope

2 vulnerabilities in this advisory, including CVE-2026-53939.

CVE-2026-53939

7.5 (High)


                
                  CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Recommended: 8 products

Open the full advisory

SUSE-SU-2026:4237-1

Vulnerability from csaf_suse - Published: 2026-09-17 11:47 - Updated: 2026-09-17 18:37

Summary

Security update for cjose

Severity

Important

Scope

2 vulnerabilities in this advisory, including CVE-2026-53939.

CVE-2026-53939

7.5 (High)


                
                  CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Recommended: 17 products

Open the full advisory

UBUNTU-CVE-2026-53939 (CVE-2026-53939)

Vulnerability from osv_ubuntu – Published: 2026-09-09 00:17 – Updated: 2026-09-16 11:36 – Source website

Details

OpenIDC/cjose is a C library implementing the Javascript Object Signing and Encryption (JOSE). In versions 0.6.1 through 0.6.2.5, when cjose encrypts a JWE using an AES-CBC-HMAC content-encryption algorithm (A128CBC-HS256, A192CBC-HS384, or A256CBC-HS512) together with any key-management algorithm that generates a fresh content-encryption key (CEK), the CEK is all zero bytes instead of being randomly generated. The resulting JWE is therefore encrypted and authenticated under a fixed, publicly known key, so anyone who obtains the JWE can recover the plaintext and forge or modify the content. This is fixed in version 0.6.2.6 by _cjose_jwe_set_cek_aes_cbc() generating the CEK from RAND_bytes. A regression test asserts that the encrypted_key differs across two encryptions for each AES-CBC-HMAC variant. Until upgrading, for data encrypted with cjose, three options are available. Use an AES-GCM enc (A128GCM / A192GCM / A256GCM) instead of an AES-CBC-HMAC enc, use alg=dir with a caller-supplied CEK, or avoid using cjose for JWE encryption with the affected algorithm pair. These are mitigations for new ciphertexts only; data already encrypted under the zero key remains compromised and should be re-encrypted (and any secrets it contained rotated).

Severity

9.1 (Critical)


                    
                      CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

N/A (UNKNOWN)


                    
                      medium

References

URL

Type

	https://ubuntu.com/security/CVE-2026-53939	REPORT
	https://www.cve.org/CVERecord?id=CVE-2026-53939	REPORT

JSON

To clipboard

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libcjose0",
            "binary_version": "0.6.0+dfsg1-1ubuntu0.1~esm1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:18.04:LTS",
        "name": "cjose",
        "purl": "pkg:deb/ubuntu/cjose@0.6.0+dfsg1-1ubuntu0.1~esm1?arch=source\u0026distro=esm-apps/bionic"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "0.4.1-3ubuntu1",
        "0.5.1+dfsg1-1",
        "0.5.1+dfsg1-2",
        "0.5.1+dfsg1-2build1",
        "0.6.0+dfsg1-1",
        "0.6.0+dfsg1-1ubuntu0.1~esm1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libcjose0",
            "binary_version": "0.6.1+dfsg1-1ubuntu0.1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:20.04:LTS",
        "name": "cjose",
        "purl": "pkg:deb/ubuntu/cjose@0.6.1+dfsg1-1ubuntu0.1?arch=source\u0026distro=focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "0.6.1+dfsg1-1",
        "0.6.1+dfsg1-1ubuntu0.1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libcjose0",
            "binary_version": "0.6.1+dfsg1-3ubuntu1.1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:22.04:LTS",
        "name": "cjose",
        "purl": "pkg:deb/ubuntu/cjose@0.6.1+dfsg1-3ubuntu1.1?arch=source\u0026distro=jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "0.6.1+dfsg1-1",
        "0.6.1+dfsg1-3",
        "0.6.1+dfsg1-3ubuntu1",
        "0.6.1+dfsg1-3ubuntu1.1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libcjose0",
            "binary_version": "0.6.2.2-1build3"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:24.04:LTS",
        "name": "cjose",
        "purl": "pkg:deb/ubuntu/cjose@0.6.2.2-1build3?arch=source\u0026distro=noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "0.6.2.2-1",
        "0.6.2.2-1build1",
        "0.6.2.2-1build2",
        "0.6.2.2-1build3"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libcjose0",
            "binary_version": "0.6.2.4-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:26.04:LTS",
        "name": "cjose",
        "purl": "pkg:deb/ubuntu/cjose@0.6.2.4-1?arch=source\u0026distro=resolute"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "0.6.2.3-1",
        "0.6.2.4-1"
      ]
    }
  ],
  "aliases": [],
  "details": "OpenIDC/cjose is a C library implementing the Javascript Object Signing and Encryption (JOSE). In versions 0.6.1 through 0.6.2.5, when cjose encrypts a JWE using an AES-CBC-HMAC content-encryption algorithm (`A128CBC-HS256`, `A192CBC-HS384`, or `A256CBC-HS512`) together with any key-management algorithm that generates a fresh content-encryption key (CEK), the CEK is all zero bytes instead of being randomly generated. The resulting JWE is therefore encrypted and authenticated under a fixed, publicly known key, so anyone who obtains the JWE can recover the plaintext and forge or modify the content. This is fixed in version 0.6.2.6 by `_cjose_jwe_set_cek_aes_cbc()` generating the CEK from `RAND_bytes`. A regression test asserts that the `encrypted_key` differs across two encryptions for each AES-CBC-HMAC variant. Until upgrading, for data encrypted with cjose, three options are available. Use an AES-GCM `enc` (`A128GCM` / `A192GCM` / `A256GCM`) instead of an AES-CBC-HMAC `enc`,  use `alg=dir` with a caller-supplied CEK, or avoid using cjose for JWE encryption with the affected algorithm pair. These are mitigations for new ciphertexts only; data already encrypted under the zero key remains compromised and should be re-encrypted (and any secrets it contained rotated).",
  "id": "UBUNTU-CVE-2026-53939",
  "modified": "2026-09-16T11:36:38Z",
  "published": "2026-09-09T00:17:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-53939"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-53939"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-53939"
  ]
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

CVE-2026-53939 (GCVE-0-2026-53939)

FKIE_CVE-2026-53939

OPENSUSE-SU-2026:11784-1

SUSE-SU-2026:4237-1

UBUNTU-CVE-2026-53939 (CVE-2026-53939)

Tags

Sightings

Nomenclature

Related by attack behaviour