Altcha Proof-of-Work obfuscation mode cryptanalytic break

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.

Recommendation

No fix is available yet. Followings are affected versions:

• >= 0.8.0, <= 2.2.4

References

• GHSA-mpmc-qchh-r9q8
• altcha.org
• CVE-2025-65849
• CWE-327
• CAPEC-310
• OWASP 2021-A2
• OWASP 2021-A6

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• Finance.js vulnerable to DoS via the seekZero() parameter - CVE-2025-56572
• jsPDF Bypass Regular Expression Denial of Service (ReDoS) - CVE-2025-29907

Tags:

npm

altcha