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Vulnerabilities

Vulnerability · CVE-2025-68113

ALTCHA is privacy-first software for captcha and bot protection.

Published Dec 16, 2025 · catalog updated Dec 16, 2025 · ALTCHA is privacy-first software

Last checked Nov 2, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2025-68113. EPSS is 0.46%. Act only if a listed version of ALTCHA is privacy-first software is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (ALTCHA is privacy-first software).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Medium6.5
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.46%
Remediation
Version ranges on file
Affected products
vendor altcha-org altcha-lib < 1.4.1

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 su

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • vendor altcha-org altcha-lib < 1.4.1< 1.4.1

How to fix CVE-2025-68113

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2025-68113. EPSS is 0.46%. Act only if a listed version of ALTCHA is privacy-first software is installed.

Which versions are affected?

Compare what you have installed with altcha-org altcha-lib < 1.4.1 < 1.4.1. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

No weakness class is stored. EPSS 0.46%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Dec 16, 2025 · EUVD

    Detected

    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 previousl

  2. Dec 16, 2025 · EUVD

    Updated

    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 previousl

Sources

  • CVE.orgVulnerability recordCVE-2025-68113

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2025-68113

    30-day exploitation probability 0.46%

    first.org
  • EUVDVulnerability recordEUVD-2025-203484

    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, allowin

    euvd.enisa.europa.eu

References

Freshness

Last verified in this catalog Nov 2, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • FIRST EPSSNov 2, 2026
  • CVE.orgNov 2, 2026
  • EUVDNov 1, 2026