CVE-2017-20189 — In Clojure before 1

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.

01What is this vulnerability?

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.

02Affected products

Vendor	Product	Versions
n	a / n/a	n/a

03Active exploitation status

Not currently listed on the CISA Known Exploited Vulnerabilities (KEV) catalog. EPSS is the best forward-looking signal — see the EPSS row above.

04Recommended remediation

• Patch to a fixed version listed in the vendor advisory (see references below).
• Mitigate with WAF rules, network egress filters, or feature flags where the patch is not yet available.
• Hunt historical logs for exploitation indicators — see Detection signatures below.

05Technical details

For the full vendor write-up, exploit chains, and reference implementations, see the references list in section 09.

06Detection signatures

Ask SARA in chat to draft a starting detection for this CVE in your stack of choice.

07Related CVEs

No directly-cited follow-up CVEs in the KB record for this advisory. The references list in section 09 carries the vendor cross-references.

08Timeline

• Published: 2024-01-22T00:00:00.000Z
• Last modified: 2025-11-03T21:44:02.825Z

09References

• hackmd.io — https://hackmd.io/%40fe1w0/HyefvRQKp
• clojure.atlassian.net — https://clojure.atlassian.net/browse/CLJ-2204
• github.com — https://github.com/frohoff/ysoserial/pull/68/files
• github.com — https://github.com/clojure/clojure/commit/271674c9b484d798484d134a5ac40a6df15d3a…
• security.snyk.io — https://security.snyk.io/vuln/SNYK-JAVA-ORGCLOJURE-5740378