CVE-2017-20189: In Clojure before 1.9.0, classes can be used to construct a serialized object that executes arbitrary code upo

Q: How do I fix CVE-2017-20189?

clojure: upgrade to 1.9.0. Exact commands for each OS are on this page.

Q: Is CVE-2017-20189 being exploited?

CVE-2017-20189 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2017-20189 affect?

CVE-2017-20189 affects clojure. Severity is critical (CVSS 9.8). In Clojure before 1.9.0, classes can be used to construct a serialized object that executes arbitrary code upon deserialization. This is relevant if a server deserializes untrusted objects.

Q: How urgent is CVE-2017-20189?

Priority 62/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action

This week

CRITICAL 9.8REMOTEUPGRADE

CVE-2017-20189 is a critical-severity flaw (CVSS 9.8) affecting clojure. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

In Clojure before 1.9.0, classes can be used to construct a serialized object that executes arbitrary code upon deserialization. This is relevant if a server deserializes untrusted objects.

Why this priority

Critical severity
Public exploit reference
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	1.3% (top 29%)
CISA exploited list	No
Weakness	CWE-502
Published	2024-01-22
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: clojure

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

Am I affected?

Timeline

2024-01-22 06:15 UTCPublished CVE record published
2026-06-17 01:15 UTCUpdated Record last modified

clojure clojure UPGRADE

Affected: < 1.9.0

Fixed in: 1.9.0

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy clojure || rpm -q clojure || clojure --version

2. UPGRADE to 1.9.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade clojure

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade clojure

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

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-2017-20189?

clojure: upgrade to 1.9.0. Exact commands for each OS are on this page.

Is CVE-2017-20189 being exploited?

CVE-2017-20189 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-2017-20189 affect?

CVE-2017-20189 affects clojure. Severity is critical (CVSS 9.8). In Clojure before 1.9.0, classes can be used to construct a serialized object that executes arbitrary code upon deserialization. This is relevant if a server deserializes untrusted objects.

How urgent is CVE-2017-20189?

Priority 62/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action

Related CVEs

CVE-2024-22871 HIGH 7.5 UPGRADE MITIGATE An issue in Clojure versions 1.20 to 1.12.0-alpha5 allows an attacker to cause a denial of service (DoS) via t

References

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