Vulnerability-Lookup

CVE-2026-44900 (GCVE-0-2026-44900)

Vulnerability from cvelistv5 – Published: 2026-05-26 21:04 – Updated: 2026-05-28 14:12

Title

epa4all-client: VAU Signature bypass

Summary

epa4all-client is the Java Client for epa4all / ePA 3.0 in the Telematik Infrastruktur. Prior to 1.2.1, in SignedPublicKeysTrustValidatorImpl.isTrusted(), the ECDSA signature verification at line 45 discards the boolean return value of Signature.verify(). The method performs certificate chain validation, OCSP check, and signature algorithm setup, but never checks whether the signature actually matches. For any structurally valid signature, it returns true. This vulnerability is fixed in 1.2.1.

Severity

8.1 (High)


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

SSVC

Exploitation: none Automatable: no Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-05-28 14:12 UTC

CWE

CWE-295 - Improper Certificate Validation

Assigner

GitHub_M

References

2 references

URL	Tags
https://github.com/oviva-ag/epa4all-client/securi…	x_refsource_CONFIRM
https://github.com/oviva-ag/epa4all-client/pull/34	x_refsource_MISC

Impacted products

2 products

Vendor	Product	Version
oviva-ag	epa4all-client	Affected: < 1.2.1
com.oviva.telematik	epa4all-client	Affected: < 1.2.1

Show details on NVD website

JSON

To clipboard

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                "id": "CVE-2026-44900",
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        }
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FKIE_CVE-2026-44900

Vulnerability from fkie_nvd - Published: 2026-05-26 22:16 - Updated: 2026-06-17 10:51

Severity

8.1 (High) - CVSS:3.1/AV:A/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/oviva-ag/epa4all-client/pull/34
	security-advisories@github.com	https://github.com/oviva-ag/epa4all-client/security/advisories/GHSA-g8r3-5hwf-qp96

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "epa4all-client",
          "vendor": "oviva-ag",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 1.2.1"
            }
          ]
        },
        {
          "product": "epa4all-client",
          "vendor": "com.oviva.telematik",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 1.2.1"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "epa4all-client is the Java Client for epa4all / ePA 3.0 in the Telematik Infrastruktur. Prior to 1.2.1, in  SignedPublicKeysTrustValidatorImpl.isTrusted(), the ECDSA signature verification at line 45 discards the boolean return value of Signature.verify(). The method performs certificate chain validation, OCSP check, and signature algorithm setup, but never checks whether the signature actually matches. For any structurally valid signature, it returns true.  This vulnerability is fixed in 1.2.1."
    }
  ],
  "id": "CVE-2026-44900",
  "lastModified": "2026-06-17T10:51:30.397",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "ADJACENT_NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 8.1,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 5.2,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-44900",
          "options": [
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              "exploitation": "none"
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            {
              "automatable": "no"
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          "role": "CISA Coordinator",
          "timestamp": "2026-05-28T14:12:19.128422Z",
          "version": "2.0.3"
        }
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  },
  "published": "2026-05-26T22:16:42.873",
  "references": [
    {
      "source": "security-advisories@github.com",
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    },
    {
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    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Deferred",
  "weaknesses": [
    {
      "description": [
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          "lang": "en",
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      "type": "Secondary"
    }
  ]
}

GHSA-G8R3-5HWF-QP96

Vulnerability from github – Published: 2026-05-08 23:47 – Updated: 2026-06-08 23:34

Summary

epa4all-client has a VAU Signature bypass

Details

Impact

In SignedPublicKeysTrustValidatorImpl.isTrusted(), the ECDSA signature verification at line 45 discards the boolean return value of Signature.verify(). The method performs certificate chain validation, OCSP check, and signature algorithm setup, but never checks whether the signature actually matches. For any structurally valid signature, it returns true.

Patches

Patched in #34.

Workarounds

None.

Resources

MS-OVIVA-EPA4ALL-d76aec

Credits

Machine Spirits (contact@machinespirits.de) - Dr. rer. nat. Simon Weber - Dipl.-Inf. Volker Schönefeld - Chiara Fliegner

Severity

8.1 (High)


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

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 1.2.0"
      },
      "package": {
        "ecosystem": "Maven",
        "name": "com.oviva.telematik:epa4all-client"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.2.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-44900"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-295"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-08T23:47:12Z",
    "nvd_published_at": "2026-05-26T22:16:42Z",
    "severity": "HIGH"
  },
  "details": "### Impact\nIn SignedPublicKeysTrustValidatorImpl.isTrusted(), the ECDSA signature verification at line 45 discards the boolean return value of Signature.verify(). The method performs certificate chain validation, OCSP check, and signature algorithm setup, but never checks whether the signature actually matches. For any structurally valid signature, it returns true.\n\n### Patches\nPatched in [#34](https://github.com/oviva-ag/epa4all-client/pull/34).\n\n### Workarounds\nNone.\n\n### Resources\n- [MS-OVIVA-EPA4ALL-d76aec](https://www.machinespirits.com/advisory/d76aec/)\n\n### Credits\n\n[Machine Spirits](https://machinespirits.com) (contact@machinespirits.de)\n- Dr. rer. nat. Simon Weber\n- Dipl.-Inf. Volker Sch\u00f6nefeld\n- Chiara Fliegner",
  "id": "GHSA-g8r3-5hwf-qp96",
  "modified": "2026-06-08T23:34:59Z",
  "published": "2026-05-08T23:47:12Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/oviva-ag/epa4all-client/security/advisories/GHSA-g8r3-5hwf-qp96"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-44900"
    },
    {
      "type": "WEB",
      "url": "https://github.com/oviva-ag/epa4all-client/pull/34"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/oviva-ag/epa4all-client"
    },
    {
      "type": "WEB",
      "url": "https://www.machinespirits.com/advisory/d76aec"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "epa4all-client has a VAU Signature bypass"
}

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.

Action not permitted

CVE-2026-44900 (GCVE-0-2026-44900)

FKIE_CVE-2026-44900

GHSA-G8R3-5HWF-QP96

Impact

Patches

Workarounds

Resources

Credits

Tags

Sightings

Nomenclature