CVE-2025-65849
CVE-2025-65849 is a critical-severity vulnerability with a CVSS 3.x base score of 9.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-327.
Key facts
- Severity: Critical (CVSS 3.x base score 9.1)
- EPSS exploit prediction: 0% (9th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2025-201806
- Weakness: CWE-327
- Published:
- Last modified:
Description
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. NOTE: this is disputed by the Supplier because the product's objective is "to discourage automated scraping / bots, not guarantee resistance to determined attackers." The documentation states “the goal is not to provide a secure cryptographic algorithm but to use a proof-of-work mechanism that allows any capable device to decrypt the hidden data.”
Frequently asked questions
- What is CVE-2025-65849?
- 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. NOTE: this is disputed by the Supplier because the product's objective is "to discourage automated scraping / bots, not guarantee resistance to determined attackers." The documentation states “the goal is not to provide a secure cryptographic algorithm but to use a proof-of-work mechanism that allows any capable device to decrypt the hidden data.”
- How severe is CVE-2025-65849?
- CVE-2025-65849 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.
- Is CVE-2025-65849 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (9th percentile), an estimate of the probability of exploitation in the next 30 days.
- How do I fix CVE-2025-65849?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
- Does CVE-2025-65849 have an EU (EUVD) identifier?
- Yes. CVE-2025-65849 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-201806.
- When was CVE-2025-65849 published?
- CVE-2025-65849 was published on 2025-12-08 and last updated on 2026-06-17.
References
- https://altcha.org/docs/v2/obfuscation/
- https://github.com/altcha-org/altcha/blob/154f874cbcdd4e639783463130d13988a2bd1bdc/src/helpers.ts#L170-L194
- https://github.com/eternal-flame-AD/altcha-deobfs
Other CWE-327 (Use of a Broken or Risky Cryptographic Algorithm) vulnerabilities
- CVE-2026-50086 — Critical (CVSS 10.0): The Aqara IAM/SSO gateway (gw-builder.aqara.com) exposes bidirectional AES round-trups against the platform's signing…
- CVE-2026-21718 — Critical (CVSS 10.0): An authentication bypass vulnerability exists in Copeland XWEB Pro version 1.12.1 and prior, enabling any attackers to…
- CVE-2025-54426 — Critical (CVSS 9.9): Polkadot Frontier is an Ethereum and EVM compatibility layer for Polkadot and Substrate. In versions prior to commit…
- CVE-2024-51478 — Critical (CVSS 9.9): YesWiki is a wiki system written in PHP. Prior to 4.4.5, the use of a weak cryptographic algorithm and a hard-coded…
- CVE-2026-28252 — Critical (CVSS 9.8): A Use of a Broken or Risky Cryptographic Algorithm vulnerability in Trane Tracer SC, Tracer SC+, and Tracer Concierge…
- CVE-2025-13476 — Critical (CVSS 9.8): Rakuten Viber Cloak mode in Android v25.7.2.0g and Windows v25.6.0.0–v25.8.1.0 uses a static and predictable TLS…
Browse all CWE-327 (Use of a Broken or Risky Cryptographic Algorithm) vulnerabilities →