CVE-2017-20227: JAD Java Decompiler 1.5.8e-1kali1 and prior contains a stack-based buffer overflow vulnerability that allows a

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CRITICAL 9.8REMOTEDOWNGRADE

CVE-2017-20227 is a critical-severity flaw (CVSS 9.8) affecting jad java decompiler. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

JAD Java Decompiler 1.5.8e-1kali1 and prior contains a stack-based buffer overflow vulnerability that allows attackers to execute arbitrary code by supplying overly long input that exceeds buffer boundaries. Attackers can craft malicious input passed to the jad command to overflow the stack and execute a return-oriented programming chain that spawns a shell.

Why this priority

Critical severity
Public exploit reference
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	0.7% (top 48%)
CISA exploited list	No
Weakness	CWE-787
Published	2026-03-28
Last modified	2026-06-17

Publisher (CNA): VulnCheck · Vendor: varaneckas

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-03-28 12:16 UTCPublished CVE record published
2026-06-17 01:15 UTCUpdated Record last modified

varaneckas jad java decompiler DOWNGRADE

Affected: 1.5.8e-1kali1

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.5.8e-1kali1

1. Check installed version

apt-cache policy jad-java-decompiler || rpm -q jad-java-decompiler || jad-java-decompiler --version

2. No fixed release: DOWNGRADE to a release before 1.5.8e-1kali1 (Debian / Ubuntu)

apt-cache madison jad-java-decompiler sudo apt install jad-java-decompiler=<VERSION_BEFORE_1.5.8e-1kali1> sudo apt-mark hold jad-java-decompiler

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list jad-java-decompiler sudo dnf downgrade jad-java-decompiler-<VERSION_BEFORE_1.5.8e-1kali1> sudo dnf versionlock add jad-java-decompiler

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Exact fixes by distribution

A distro patch exists: prefer upgrading over downgrading.

Fedora ELN · perl-Encode · FIXED · 3.25-528.eln159 · FEDORA-2026-79991d0238 · source

sudo dnf upgrade --advisory=FEDORA-2026-79991d0238

Fedora 46 · fonttools · FIXED · 4.68.0-1.fc46 · FEDORA-2026-65d6c01c75 · source

sudo dnf upgrade --advisory=FEDORA-2026-65d6c01c75

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: www.exploit-db.com/exploits/42255

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-2017-20227?

jad java decompiler: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2017-20227 being exploited?

CVE-2017-20227 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-2017-20227 affect?

CVE-2017-20227 affects jad java decompiler. Severity is critical (CVSS 9.8). JAD Java Decompiler 1.5.8e-1kali1 and prior contains a stack-based buffer overflow vulnerability that allows attackers to execute arbitrary code by supplying overly long input that exceeds buffer boundaries. Attackers can craft malicious in

How urgent is CVE-2017-20227?

Priority 60/100. Critical severity; Public exploit reference; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action

Software pages

Java vulnerabilities

Related CVEs

CVE-2016-20049 CRITICAL 9.8 DOWNGRADE JAD 1.5.8e-1kali1 and prior contains a stack-based buffer overflow vulnerability that allows attackers to exec

References

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