CVE-2025-65849: Altcha Proof-of-Work obfuscation mode cryptanalytic break

December 8, 2025 (updated December 12, 2025)

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

altcha.org/docs/v2/obfuscation
github.com/advisories/GHSA-mpmc-qchh-r9q8
github.com/altcha-org/altcha
github.com/altcha-org/altcha/blob/154f874cbcdd4e639783463130d13988a2bd1bdc/src/helpers.ts
github.com/eternal-flame-AD/altcha-deobfs
nvd.nist.gov/vuln/detail/CVE-2025-65849

Code Behaviors & Features

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