Vulnerability-Lookup

CVE-2026-74900 (GCVE-0-2026-74900)

Vulnerability from cvelistv5 – Published: 2026-08-17 11:04 – Updated: 2026-08-17 12:47

Title

openssl_encrypt before 1.4.0 Weak Shared Secret via PQC Simulation Mode

Summary

openssl_encrypt versions before 1.4.0 contain a critical vulnerability in pqc.py where KEM decapsulation failures silently fall back to simulation mode, generating a deterministic shared secret from only 16 bytes of the private key and publicly available encapsulated key data. Attackers who obtain 16 bytes of the private key can compute the shared secret and decrypt all ciphertext, as the fallback triggers on any KEM failure without raising an error.

Severity

9.3 (Critical)


                        
                          CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

9.8 (Critical)


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

SSVC

Exploitation: none Automatable: yes Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-08-17 12:46 UTC

CWE

CWE-391 - Unchecked Error Condition

Assigner

VulnCheck

References

2 references

URL	Tags
https://github.com/jahlives/openssl_encrypt/secur…	vendor-advisory
https://www.vulncheck.com/advisories/openssl-encr…	third-party-advisory

Impacted products

1 product

Vendor	Product	Version	CPE status
jahlives	openssl_encrypt	Affected: 0 , < 1.4.0 (semver) Unaffected: 1.4.0 (semver)	guessed

Date Public

2026-02-10 00:00

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-74900

Vulnerability from fkie_nvd - Published: 2026-08-17 11:16 - Updated: 2026-08-17 13:16

Severity

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

Summary

References

	URL	Tags
	disclosure@vulncheck.com	https://github.com/jahlives/openssl_encrypt/security/advisories/GHSA-p3gq-pcg9-qvfv
	disclosure@vulncheck.com	https://www.vulncheck.com/advisories/openssl-encrypt-before-weak-shared-secret-via-pqc-simulation-mode

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "packageURL": "pkg:pypi/openssl_encrypt",
          "product": "openssl_encrypt",
          "vendor": "jahlives",
          "versions": [
            {
              "lessThan": "1.4.0",
              "status": "affected",
              "version": "0",
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    }
  ],
  "id": "CVE-2026-74900",
  "lastModified": "2026-08-17T13:16:53.973",
  "metrics": {
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        "impactScore": 5.9,
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        "type": "Secondary"
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}

GHSA-7QJ7-JV8M-RFJW

Vulnerability from github – Published: 2026-08-17 12:32 – Updated: 2026-08-17 12:32

Details

Severity

9.8 (Critical)


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

9.3 (Critical)


                  
                    CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Show details on source website

JSON

To clipboard

{
  "affected": [],
  "aliases": [
    "CVE-2026-74900"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-391"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-17T11:16:45Z",
    "severity": "CRITICAL"
  },
  "details": "openssl_encrypt versions before 1.4.0 contain a critical vulnerability in pqc.py where KEM decapsulation failures silently fall back to simulation mode, generating a deterministic shared secret from only 16 bytes of the private key and publicly available encapsulated key data. Attackers who obtain 16 bytes of the private key can compute the shared secret and decrypt all ciphertext, as the fallback triggers on any KEM failure without raising an error.",
  "id": "GHSA-7qj7-jv8m-rfjw",
  "modified": "2026-08-17T12:32:27Z",
  "published": "2026-08-17T12:32:27Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/jahlives/openssl_encrypt/security/advisories/GHSA-p3gq-pcg9-qvfv"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-74900"
    },
    {
      "type": "WEB",
      "url": "https://www.vulncheck.com/advisories/openssl-encrypt-before-weak-shared-secret-via-pqc-simulation-mode"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
      "type": "CVSS_V4"
    }
  ]
}

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-2026-74900 (GCVE-0-2026-74900)

FKIE_CVE-2026-74900

GHSA-7QJ7-JV8M-RFJW

Tags

Sightings

Nomenclature