Description
A cryptanalytic break in Altcha Proof-of-Work obfuscation mode version 0.8.0 and later allows for remote visitors to recover the Proof-of-Work nonce in constant time via mathematical deduction. NOTE: this is disputed by the Supplier because the product's objective is "to discourage automated scraping / bots, not guarantee resistance to determined attackers." The documentation states “the goal is not to provide a secure cryptographic algorithm but to use a proof-of-work mechanism that allows any capable device to decrypt the hidden data.”
Published: 2025-12-08
Score: 9.1 Critical
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

Analysis and contextual insights are available on OpenCVE Cloud.

Remediation

No vendor fix or workaround currently provided.

Additional remediation guidance may be available on OpenCVE Cloud.

Tracking

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-mpmc-qchh-r9q8 Altcha Proof-of-Work obfuscation mode cryptanalytic break
History

Thu, 11 Dec 2025 15:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-327
Metrics cvssV3_1

{'score': 9.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N'}

ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}


Thu, 11 Dec 2025 14:45:00 +0000

Type Values Removed Values Added
Description A cryptanalytic break in Altcha Proof-of-Work obfuscation mode version 0.8.0 and later allows for remote visitors to recover the Proof-of-Work nonce in constant time via mathematical deduction. A cryptanalytic break in Altcha Proof-of-Work obfuscation mode version 0.8.0 and later allows for remote visitors to recover the Proof-of-Work nonce in constant time via mathematical deduction. NOTE: this is disputed by the Supplier because the product's objective is "to discourage automated scraping / bots, not guarantee resistance to determined attackers." The documentation states “the goal is not to provide a secure cryptographic algorithm but to use a proof-of-work mechanism that allows any capable device to decrypt the hidden data.”

Tue, 09 Dec 2025 10:30:00 +0000

Type Values Removed Values Added
First Time appeared Altcha
Altcha altcha
Vendors & Products Altcha
Altcha altcha

Mon, 08 Dec 2025 19:00:00 +0000

Type Values Removed Values Added
Description A cryptanalytic break in Altcha Proof-of-Work obfuscation mode version 0.8.0 and later allows for remote visitors to recover the Proof-of-Work nonce in constant time via mathematical deduction.
References

cve-icon MITRE

Status: PUBLISHED

Assigner: mitre

Published:

Updated: 2025-12-11T14:36:52.373Z

Reserved: 2025-11-18T00:00:00.000Z

Link: CVE-2025-65849

cve-icon Vulnrichment

Updated: 2025-12-09T20:01:55.406Z

cve-icon NVD

Status : Deferred

Published: 2025-12-08T19:15:50.817

Modified: 2026-04-15T00:35:42.020

Link: CVE-2025-65849

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2025-12-09T10:26:36Z

Weaknesses