Security Digest · Vulnerability record
CVE-2017-20189: Clojure classes can be used to craft a serialized object that runs arbitrary code on deserialization
In Clojure before 1.9.0, classes can be used to construct a serialized object that executes arbitrary code upon deserialization.
CVSS 9.8 Critical EPSS 1.3% · p71
Should you act?
Critical and remotely reachable
No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.
- Not in CISA KEV, but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 1.3%, percentile 71: FIRST’s model estimates a 1.3% chance of exploitation activity in the next 30 days, higher than 71% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes
org.clojure:clojure(Maven) < 1.9.0, fixed in 1.9.0. Check your lockfile, including transitive dependencies.
What it is
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.
From the GitHub advisory
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.
Weakness type: CWE-502.
Product: org.clojure:clojure (Maven) · Assigned by: mitre · Published: 2024-01-22
Affected and fixed versions
| Ecosystem | Package | Vulnerable | First fixed |
|---|---|---|---|
| Maven | org.clojure:clojure | < 1.9.0 | 1.9.0 |
| Vendor | Product | Affected versions (per CVE record) |
|---|---|---|
| n/a | n/a | see vendor advisory |
Severity scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| CISA-ADP | 3.1 | 9.8 Critical | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| GitHub | 3.1 | 9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
- Attack vector: network (remotely reachable)
- Attack complexity: low
- Privileges required: none (no login)
- User interaction: none
- Scope: unchanged
CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.
Exploitation and urgency
- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc, automatable yes, technical impact total.
- FIRST EPSS (model of 2026-10-21): 1.33% probability of exploitation activity in the next 30 days; percentile 71.
Timeline
- — CVE record published by mitre
- — GitHub-reviewed advisory GHSA-jgxc-8mwq-9xqw published (critical)
- — CVE record last updated
Sources and references
Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.
Vulnerability records
- GitHub Advisory GHSA-jgxc-8mwq-9xqw github.com
- CVE.org record CVE-2017-20189 cve.org
- NVD entry CVE-2017-20189 nvd.nist.gov
Other references from the CVE record and advisory
- hackmd.io hackmd.io
- clojure.atlassian.net clojure.atlassian.net
- github.com github.com
- github.com github.com
- security.snyk.io security.snyk.io
- security.netapp.com security.netapp.com
- groups.google.com groups.google.com