CVE-2025-68113

Workarounds

As a mitigation, implementations may append a delimiter to the end of the salt value prior to HMAC computation (for example, <salt>?expires=<time>&). This prevents ambiguity between parameters and the nonce and is backward-compatible with existing implementations, as the delimiter is treated as a standard URL parameter separator.

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. This may allow previously solved challenges to be reused beyond their intended lifetime, depending on server-side replay handling and deployment assumptions.

The vulnerability primarily impacts abuse-prevention mechanisms such as rate limiting and bot mitigation. It does not directly affect data confidentiality or integrity.

CVE-2025-68113 has a CVSS score of 6.5 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.4.1, 1.3.1, 1.0.0, 1.3.0); upgrading removes the vulnerable code path.

Kodem intelligence

This issue has been addressed by enforcing explicit semantic separation between challenge parameters and the nonce during HMAC computation.

Users are advised to upgrade to patched versions.

1. What is CVE-2025-68113? CVE-2025-68113 is a medium-severity security vulnerability in altcha-lib (npm), affecting versions < 1.4.1. It is fixed in 1.4.1, 1.3.1, 1.0.0, 1.3.0.
2. How severe is CVE-2025-68113? CVE-2025-68113 has a CVSS score of 6.5 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which packages are affected by CVE-2025-68113?
   • altcha-lib (npm) (versions < 1.4.1)
   • altcha-org/altcha (composer) (versions < 1.3.1)
   • github.com/altcha-org/altcha-lib-go (go) (versions < 1.0.0)
   • org.altcha:altcha (maven) (versions < 1.3.0)
   • altcha (rubygems) (versions < 1.0.0)
4. Is there a fix for CVE-2025-68113? Yes. CVE-2025-68113 is fixed in 1.4.1, 1.3.1, 1.0.0, 1.3.0. Upgrade to this version or later.
5. Is CVE-2025-68113 exploitable, and should I be worried? Whether CVE-2025-68113 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2025-68113 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2025-68113?
   • Upgrade altcha-lib to 1.4.1 or later
   • Upgrade altcha-org/altcha to 1.3.1 or later
   • Upgrade github.com/altcha-org/altcha-lib-go to 1.0.0 or later
   • Upgrade org.altcha:altcha to 1.3.0 or later
   • Upgrade altcha to 1.0.0 or later
   • Upgrade altcha to 1.0.0 or later
   • Upgrade altcha to 1.0.0 or later