CVE-2024-5986 — h2o-3 Arbitrary File Write via Parse and Export Endpoints
A vulnerability in h2oai/h2o-3 version 3.46.0.1 allows remote attackers to write arbitrary data to any file on the server. This is achieved by exploiting the `/3/Parse` endpoint to inject attacker-controlled data as the header of an empty file, which is then exported using the `/3/Frames/framename/export` endpoint. The impact of this vulnerability includes the potential for remote code execution and complete access to the system running h2o-3, as attackers can overwrite critical files such as private SSH keys or script files.
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- EPSS 0.7% (30-day exploitation probability)+8
- Technical severity (critical)+10
- Automatable exploitation (SSVC)+3
The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.
CISA SSVC assessment CISA
Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.
First 24 hours
Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.
- Identify exposed assets running the affected vendor/product/version combinations (H2oai H2o-3).
- The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
- No fix documented in the sources: reduce exposure and monitor the vendor advisory.
- Search available logs for exploit probes, errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Every base score collected
Sources score independently and may disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 9.1 | CVSS 3.0 | Critical | 3.9 | 5.2 | security@huntr.dev via NIST National Vulnerability Database |
| 9.1 | CVSS 3.0 | Critical | — | — | @huntr_ai via CVE Program (cve.org) e CISA ADP |
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H (score shown at the top: security@huntr.dev) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
EPSS over time FIRST
Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 0.71%
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
Analysis and videos
CVE-2024-5986: h2o-3 Arbitrary File Write via Parse and Export Endpoints
CVE-2024-5986 affects h2oai/h2o-3 version 3.46.0.1 and, according to the record, allows remote attackers to write arbitrary data to files on the server. The record links this to CWE-73 and assigns a CVSS 3.0 base score of 9.1 (Critical) from the CNA security@huntr.dev. No confirmed exploitation appears in the sources consulted, and no fixed version is listed in the record.
Timeline
What happened to this CVE, newest first.
- 2026
- Affected products added · h2oai/h2oai/h2o-3
- SSVC assessment updated
- Record published
- CVSS changed · 9.1
- Source status changed · → Deferred
- Record created in this database
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 1× Official description updated · Oct 13, 2026 – Oct 13, 2026
References
1 on the record
Elsewhere on this site
Related CVEs (same products)
- Medium CVE-2026-8752 h2oai h2o-3 Rapids setproperty Primitive AstSetProperty.java exec access control May 17, 2026
- Critical CVE-2026-8751 h2oai h2o-3 JAR Model.java importBinaryModel deserialization May 17, 2026
- High CVE-2026-8750 h2oai h2o-3 ImportFile API PersistNFS.java importFiles information disclosure May 17, 2026
- Critical CVE-2026-3960 Remote Code Execution in h2oai/h2o-3 Apr 23, 2026
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No fixed version, patch or mitigation documented.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record
Text assembled only from the fields above — no additional claims.
What should defenders know first?
CVE-2024-5986 is "h2o-3 Arbitrary File Write via Parse and Export Endpoints", rated Critical. It affects H2o-3 (H2oai); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 9.1 describes technical severity. EPSS 0.71% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.
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