CVE-2026-51785: An issue in Hugo Leisink Hiawatha v.12.1 and before allows a remote attacker to execute arbitrary code via a c

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CRITICAL 9.8REMOTE

CVE-2026-51785 is a critical-severity flaw (CVSS 9.8) affecting affected software. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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

Why this priority

Critical severity
CISA SSVC: public proof of concept
CISA SSVC: automatable with total technical impact
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.1% (top 33%)
CISA exploited list	No
Weakness	CWE-94
Published	2026-07-31
Last modified	2026-10-23

Publisher (CNA): MITRE

Last updated 2026-10-23 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Timeline

2026-07-31 21:17 UTCPublished CVE record published
2026-10-23 23:10 UTCUpdated Record last modified

Exact fixes by distribution

Fedora 46 · python-openslide · FIXED · 1.4.7-1.fc46 · FEDORA-2026-336bea884e · source

sudo dnf upgrade --advisory=FEDORA-2026-336bea884e

Fedora ELN · valgrind · FIXED · 3.28.0-1.eln159 · FEDORA-2026-c593ef1d15 · source

sudo dnf upgrade --advisory=FEDORA-2026-c593ef1d15

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Write-up: fenrisk.com/hiawatha-http-smuggling

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-51785?

No fixed release is listed yet. Watch the vendor advisory and apply any mitigation shown on this page.

Is CVE-2026-51785 being exploited?

CVE-2026-51785 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-51785 affect?

CVE-2026-51785 affects affected software. Severity is critical (CVSS 9.8). An issue in Hugo Leisink Hiawatha v.12.1 and before allows a remote attacker to execute arbitrary code via a crafted request

How urgent is CVE-2026-51785?

Priority 62/100. Critical severity; CISA SSVC: public proof of concept; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action

References

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