CVE-2025-27209
CVE-2025-27209 is a high-severity vulnerability with a CVSS 3.x base score of 7.5. 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-407.
Key facts
- Severity: High (CVSS 3.x base score 7.5)
- EPSS exploit prediction: 1% (51st percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2025-21940
- Weakness: CWE-407
- Published:
- Last modified:
Description
The V8 release used in Node.js v24.0.0 has changed how string hashes are computed using rapidhash. This implementation re-introduces the HashDoS vulnerability as an attacker who can control the strings to be hashed can generate many hash collisions - an attacker can generate collisions even without knowing the hash-seed. * This vulnerability affects Node.js v24.x users.
Frequently asked questions
- What is CVE-2025-27209?
- The V8 release used in Node.js v24.0.0 has changed how string hashes are computed using rapidhash. This implementation re-introduces the HashDoS vulnerability as an attacker who can control the strings to be hashed can generate many hash collisions - an attacker can generate collisions even without knowing the hash-seed. * This vulnerability affects Node.js v24.x users.
- How severe is CVE-2025-27209?
- CVE-2025-27209 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
- Is CVE-2025-27209 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (51st percentile), an estimate of the probability of exploitation in the next 30 days.
- How do I fix CVE-2025-27209?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
- Does CVE-2025-27209 have an EU (EUVD) identifier?
- Yes. CVE-2025-27209 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-21940.
- When was CVE-2025-27209 published?
- CVE-2025-27209 was published on 2025-07-18 and last updated on 2026-06-17.
References
- https://nodejs.org/en/blog/vulnerability/july-2025-security-releases
- http://www.openwall.com/lists/oss-security/2025/07/22/2
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