Answer in brief
CVE-2025-68113 records a Medium severity (CVSS 6.5) vulnerability in ALTCHA Proof-of-Work Vulnerable to Challenge Splicing and Replay. The current sources do not mark it as known exploited. The current feed maps github.com/altcha-org/altcha-lib-go (go), altcha (hex), org.altcha:altcha (maven), altcha-lib (npm) and additional mapped packages. Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 6.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps github.com/altcha-org/altcha-lib-go (go), altcha (hex), org.altcha:altcha (maven), altcha-lib (npm) and additional mapped packages. Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| github.com/altcha-org/altcha-lib-gogo | >=0 <1.0.0 | 1.0.0 |
| altchahex | >=0 <1.0.0 | 1.0.0 |
| org.altcha:altchamaven | >=0 <1.3.0 | 1.3.0 |
| altcha-libnpm | >=0 <1.4.1 | 1.4.1 |
| altcha-org/altchapackagist | >=0 <1.3.1 | 1.3.1 |
| altchapypi | >=0 <1.0.0 | 1.0.0 |
| altcharubygems | >=0 <1.0.0 | 1.0.0 |
Published upstream
Dec 16, 2025
Evidence: source:nvd:source_dates:source-dates:recordSource modified
Oct 7, 2026
Evidence: source:nvd:source_dates:source-dates:recordFirst seen by HOL
Aug 8, 2026
ALTCHA is privacy-first software for captcha and bot protection. 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. 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, which include version 1.0.0 of the altcha Golang package, version 1.0.0 of the altcha Rubygem, version 1.0.0 of the altcha pip package, version 1.0.0 of the altcha Erlang package, version 1.4.1 of the altcha-lib npm package, version 1.3.1 of the altcha-org/altcha Composer package, and version 1.3.0 of the org.altcha:altcha Maven package. 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.
Quoted source text, attributed separately from HOL analysis.