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Fencer Vulns
critical 9.8

CVE-2026-51785 json

An issue in Hugo Leisink Hiawatha v.12.1 and before allows a remote attacker to execute arbitrary code via a crafted request

published 2026-07-31 3 mo ago modified 2026-10-23 16 d ago also EUVD-2026-51645

cvss
9.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.1%
EPSS 1.1% chance of exploitation in 30 days, percentile 67%
public exploits
0
none known

Summary

An issue in Hugo Leisink Hiawatha v.12.1 and before allows a remote attacker to execute arbitrary code via a crafted request

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
total
Assessed
3 mo ago

Exploit prediction

1.15% chance of exploitation in the next 30 days, higher than 67% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • fenrisk.com https://fenrisk.com/hiawatha-http-smuggling referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CISA ADP 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Classification

Weakness
  • CWE-94 Improper Control of Generation of Code

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.