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Fencer Vulns
medium 6.5

CVE-2024-6863 json

Encryption of Arbitrary Files with Attacker-Controlled Key in h2oai/h2o-3

published 2025-03-20 19 mo ago modified 2026-07-07 4 mo ago also GHSA-m37h-8r48-2cxj , PYSEC-2026-1442 , EUVD-2025-6964

cvss
6.5
version 3.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 29%
public exploits
0
none known

Summary

In h2oai/h2o-3 version 3.46.0, an endpoint exposing a custom EncryptionTool allows an attacker to encrypt any files on the target server with a key of their choosing. The chosen key can also be overwritten, resulting in ransomware-like behavior. This vulnerability makes it possible for an attacker to encrypt arbitrary files with keys of their choice, making it exceedingly difficult for the target to recover the keys needed for decryption.

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
19 mo ago

Exploit prediction

0.36% chance of exploitation in the next 30 days, higher than 29% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • huntr.com https://huntr.com/bounties/10f55937-0cba-4530-897f-2abf30ed5270 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.0 6.5 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L
GitHub 3.0 6.5 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L
OSV 3.0 6.5 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L

Affected packages

ecosystem package affected fixed in
pypi h2o
>=3.32.1.2, <=3.46.0
no fix listed
maven ai.h2o:h2o-core
>=3.32.1.2, <=3.46.0
no fix listed

Affected products

  • h2oai h2oai/h2o-3

Classification

Weakness
  • CWE-749 Exposed Dangerous Method or Function

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.