CVE-2016-4000

Deserialization of Untrusted Data in Jython

9.8 CriticalFix available

CVE-2016-4000 is a critical vulnerability (CVSS 9.8) in Jython Project Jython, published June 17, 2017. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 6.21%, the 93rd percentile. Fixed in org.python:jython-standalone 2.7.1b3.

Jython before 2.7.1rc1 allows attackers to execute arbitrary code via a crafted serialized PyFunction object.

Attack profile

How easy it is to exploit

Attack vector: Network
Complexity: Low
Privileges needed: None
User interaction: None

What an attacker can affect

Confidentiality: High
Integrity: High
Availability: High

Exploit likelihood

6.21%Up 2.4 points since Feb 4, 2022

What each source reports

NVD Score used 9.8

Jython before 2.7.1rc1 allows attackers to execute arbitrary code via a crafted serialized PyFunction object.

Record: CVE-2016-4000
CVSS 3.0: 9.8 CriticalCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS 2.0: 7.5 HighAV:N/AC:L/Au:N/C:P/I:P/A:P
Weakness: CWE-502
Updated: 2026-11-02

CVE List No score

Jython before 2.7.1rc1 allows attackers to execute arbitrary code via a crafted serialized PyFunction object.

Record: CVE-2016-4000
Updated: 2026-11-02

EUVDEUVD-2022-2855 No score

Jython before 2.7.1rc1 allows attackers to execute arbitrary code via a crafted serialized PyFunction object.

Record: EUVD-2022-2855
Updated: 2026-11-03

GitHub AdvisoriesGHSA-6r7r-jj8h-pq6v 9.8

Deserialization of Untrusted Data in Jython

Jython before 2.7.1b3 allows attackers to execute arbitrary code via a crafted serialized PyFunction object.

Record: GHSA-6r7r-jj8h-pq6v
CVSS 3.0: 9.8 CriticalCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness: CWE-502
Updated: 2026-11-02

OSV 9.8

Jython before 2.7.1rc1 allows attackers to execute arbitrary code via a crafted serialized PyFunction object.

Record: CVE-2016-4000
CVSS 3.0: 9.8 CriticalCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated: 2026-11-02

OSVDEBIAN-CVE-2016-4000 9.8

Jython before 2.7.1rc1 allows attackers to execute arbitrary code via a crafted serialized PyFunction object.

Record: DEBIAN-CVE-2016-4000
CVSS 3.0: 9.8 CriticalCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated: 2026-11-02

OSVGHSA-6r7r-jj8h-pq6v 9.8

Deserialization of Untrusted Data in Jython

Jython before 2.7.1b3 allows attackers to execute arbitrary code via a crafted serialized PyFunction object.

Record: GHSA-6r7r-jj8h-pq6v
CVSS 3.0: 9.8 CriticalCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness: CWE-502
Updated: 2026-11-02

OSVUBUNTU-CVE-2016-4000 9.8

Jython before 2.7.1rc1 allows attackers to execute arbitrary code via a crafted serialized PyFunction object.

Record: UBUNTU-CVE-2016-4000
CVSS 3.0: 9.8 CriticalCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated: 2026-11-02

Affected products

Affected packages

Affected packages
Package	Affected	Fixed
`org.python:jython-standalone` Maven	before 2.7.1b3	2.7.1b3
`org.python:jython` Maven	before 2.7.1b3	2.7.1b3
`jython` Debian:12	before 2.5.3-17	2.5.3-17
`jython` Debian:13	before 2.5.3-17	2.5.3-17
`jython` Debian:14	before 2.5.3-17	2.5.3-17
`jython` Debian:7	before 2.5.2-1+deb7u1, plus listed versions 2.5.2-1	2.5.2-1+deb7u1
`jython` Debian:8	before 2.5.3-3+deb8u1, plus listed versions 2.5.3-3	2.5.3-3+deb8u1
`jython` Debian:9	before 2.5.3-16+deb9u1, plus listed versions 2.5.3-16	2.5.3-16+deb9u1
`org.python:jython-standalone` Maven	before 2.7.1b3, plus listed versions 2.5.12.5.22.5.32.5.3-rc12.5.4-rc1 Show 10 moreShow less 2.7-b12.7-b22.7-b32.7-b42.7-rc12.7-rc22.7-rc32.7.02.7.1b12.7.1b2	2.7.1b3
`org.python:jython` Maven	before 2.7.1b3, plus listed versions 2.22.2-beta12.2-beta22.2-rc12.2-rc3 Show 15 moreShow less 2.2.12.5.02.5.32.5.3-rc12.5.4-rc12.7-b12.7-b22.7-b32.7-b42.7-rc12.7-rc22.7-rc32.7.02.7.1b12.7.1b2	2.7.1b3
`jython` Ubuntu:14.04:LTS	before 2.5.3-1ubuntu0.1, plus listed versions 2.5.2-22.5.3-1	2.5.3-1ubuntu0.1
`jython` Ubuntu:16.04:LTS	before 2.5.3-9ubuntu0.1, plus listed versions 2.5.3-62.5.3-72.5.3-82.5.3-9	2.5.3-9ubuntu0.1

History

History
When	Changed	Sources
2026-11-03	aliases	EUVD
2026-11-02	created	CVE List, GitHub Advisories, NVD, OSV

References

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