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CVE-2016-4864
H2O versions 2.0.3 and earlier and 2.1.0-beta2 and earlier allows remote attackers to cause a denial-of-service (DoS) via format string…
High7.5EPSS 1.8%
- Published
- Updated
- Reserved
- Assigned by
- jpcert
Description
H2O versions 2.0.3 and earlier and 2.1.0-beta2 and earlier allows remote attackers to cause a denial-of-service (DoS) via format string specifiers in a template file via fastcgi, mruby, proxy, redirect or reproxy.
Timeline
ID reserved
By jpcert
- 12 months later
· 12 months later
Published
- 7 years later
· 7 years later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| NVDNVD · Modified | 3.0 | High7.5 | CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 1.8% · top 21% of all CVEs (8 Nov 2026)
Loading the EPSS history…
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.5.
Weakness
- Format String Vulnerability
- CWE-134 (opens in a new tab)All about CWE-134 and its CVEs
Affected products
- affected versions 2.0.3 and earlier
- affected versions 2.1.0-beta2 and earlier
References (2)
- https://github.com/h2o/h2o/issues/1077 (opens in a new tab)x_refsource_CONFIRMx_transferred
- JVN#94779084 (opens in a new tab)third-party-advisoryx_refsource_JVNx_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2016-4864)Record last updated .