ALTCHA Proof-of-Work Vulnerable to Challenge Splicing and Replay

Description

A cryptographic semantic binding flaw in ALTCHA libraries allows challenge payload splicing, which may enable replay attacks. The HMAC signature does not unambiguously bind challenge parameters to the nonce, allowing an attacker to reinterpret a valid proof-of-work submission with a modified expiration value.

Recommendation

Update the altcha-lib package to the latest compatible version. Followings are version details:

• Affected version(s): < 1.4.1
• Patched version(s): 1.4.1

References

• GHSA-6gvq-jcmp-8959
• CVE-2025-68113
• CWE-115
• CWE-347
• CAPEC-310
• OWASP 2021-A2
• OWASP 2021-A6

Related Issues

• Altcha Proof-of-Work obfuscation mode cryptanalytic break - CVE-2025-65849
• Trix vulnerable to Cross-site Scripting on copy & paste - CVE-2025-46812
• Signal K Server Vulnerable to Denial of Service via Unrestricted Access Request Flooding - CVE-2025-68272
• Signal K Server Vulnerable to Unauthenticated Information Disclosure via Exposed Endpoints - CVE-2025-68273

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Tags:

npm

altcha-lib