How severe is GHSA-mjmj-j48q-9wg2?

GHSA-mjmj-j48q-9wg2 has a CVSS score of 8.3/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by GHSA-mjmj-j48q-9wg2?

GHSA-mjmj-j48q-9wg2 affects the following packages: org.yaml:snakeyaml (Maven). Ecosystems affected: Maven.

How do I fix GHSA-mjmj-j48q-9wg2?

Update org.yaml:snakeyaml to 2.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-mjmj-j48q-9wg2 is resolved across your whole dependency graph.

How do I detect GHSA-mjmj-j48q-9wg2 in my Maven dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.yaml:snakeyaml. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate GHSA-mjmj-j48q-9wg2 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against GHSA-mjmj-j48q-9wg2?

O3 pinpoints whether GHSA-mjmj-j48q-9wg2 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is GHSA-mjmj-j48q-9wg2 actively exploited in the wild?

Yes. There are 7 known exploit references for GHSA-mjmj-j48q-9wg2, including 5 in-the-wild exploitations observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for GHSA-mjmj-j48q-9wg2?

GHSA-mjmj-j48q-9wg2 has an EPSS (Exploit Prediction Scoring System) score of 99.6%, placing it in the 100th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. A score above 50% indicates significantly elevated exploitation risk — immediate patching is strongly recommended.

What type of vulnerability is GHSA-mjmj-j48q-9wg2?

GHSA-mjmj-j48q-9wg2 is classified as Improper Input Validation (CWE-20), Deserialization of Untrusted Data (CWE-502). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was GHSA-mjmj-j48q-9wg2 published, and has it been updated?

GHSA-mjmj-j48q-9wg2 was published on December 12, 2022 and was last updated on July 8, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

☕

☕ Maven

Not in CISA KEV

HIGH severity

GHSA-mjmj-j48q-9wg2

HIGH

GHSA-mjmj-j48q-9wg2 is a high-severity (CVSS 8.3) Improper Input Validation vulnerability in org.yaml:snakeyaml. 7 public exploit references exist, so weaponization risk is real. O3 Security confirms whether GHSA-mjmj-j48q-9wg2 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

SnakeYaml Constructor Deserialization Remote Code Execution

Also known asCVE-2022-1471

Published

Dec 12, 2022

Updated

Jul 8, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

7 known

Exploitation data as of Sep 8, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

Proof-of-concept exploit code exists

CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
A successful exploit gives an attacker total control of the affected component, not partial access.

Exploitation and automatability from CISA’s SSVC triage for GHSA-mjmj-j48q-9wg2.

EPSS Exploitation Probability

via FIRST.org ↗

99.6%probability of exploitation in next 30 days

Very High Risk0.00%

Lower risk than most CVEs100th percentile — riskier than 100% of all scored CVEsHighest risk

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

How urgent is this, really

GHSA-mjmj-j48q-9wg2 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE sits: patch-first territory.

Where this sits among everything scored

Of 370,894 CVEs with a current EPSS score, this one falls in the ≥ 90% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.

Real-World Exposure

1 pkg affected

☕org.yaml:snakeyaml

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

Description

Summary

SnakeYaml's Constructor class, which inherits from SafeConstructor, allows any type be deserialized given the following line:

new Yaml(new Constructor(TestDataClass.class)).load(yamlContent);

Types do not have to match the types of properties in the target class. A ConstructorException is thrown, but only after a malicious payload is deserialized.

Severity

High, lack of type checks during deserialization allows remote code execution.

Proof of Concept

Execute bash run.sh. The PoC uses Constructor to deserialize a payload for RCE. RCE is demonstrated by using a payload which performs a http request to http://127.0.0.1:8000.

Example output of successful run of proof of concept:

$ bash run.sh

[+] Downloading snakeyaml if needed
[+] Starting mock HTTP server on 127.0.0.1:8000 to demonstrate RCE
nc: no process found
[+] Compiling and running Proof of Concept, which a payload that sends a HTTP request to mock web server.
[+] An exception is expected.
Exception:
Cannot create property=payload for JavaBean=Main$TestDataClass@3cbbc1e0
 in 'string', line 1, column 1:
    payload: !!javax.script.ScriptEn ... 
    ^
Can not set java.lang.String field Main$TestDataClass.payload to javax.script.ScriptEngineManager
 in 'string', line 1, column 10:
    payload: !!javax.script.ScriptEngineManag ... 
             ^

	at org.yaml.snakeyaml.constructor.Constructor$ConstructMapping.constructJavaBean2ndStep(Constructor.java:291)
	at org.yaml.snakeyaml.constructor.Constructor$ConstructMapping.construct(Constructor.java:172)
	at org.yaml.snakeyaml.constructor.Constructor$ConstructYamlObject.construct(Constructor.java:332)
	at org.yaml.snakeyaml.constructor.BaseConstructor.constructObjectNoCheck(BaseConstructor.java:230)
	at org.yaml.snakeyaml.constructor.BaseConstructor.constructObject(BaseConstructor.java:220)
	at org.yaml.snakeyaml.constructor.BaseConstructor.constructDocument(BaseConstructor.java:174)
	at org.yaml.snakeyaml.constructor.BaseConstructor.getSingleData(BaseConstructor.java:158)
	at org.yaml.snakeyaml.Yaml.loadFromReader(Yaml.java:491)
	at org.yaml.snakeyaml.Yaml.load(Yaml.java:416)
	at Main.main(Main.java:37)
Caused by: java.lang.IllegalArgumentException: Can not set java.lang.String field Main$TestDataClass.payload to javax.script.ScriptEngineManager
	at java.base/jdk.internal.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:167)
	at java.base/jdk.internal.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:171)
	at java.base/jdk.internal.reflect.UnsafeObjectFieldAccessorImpl.set(UnsafeObjectFieldAccessorImpl.java:81)
	at java.base/java.lang.reflect.Field.set(Field.java:780)
	at org.yaml.snakeyaml.introspector.FieldProperty.set(FieldProperty.java:44)
	at org.yaml.snakeyaml.constructor.Constructor$ConstructMapping.constructJavaBean2ndStep(Constructor.java:286)
	... 9 more
[+] Dumping Received HTTP Request. Will not be empty if PoC worked
GET /proof-of-concept HTTP/1.1
User-Agent: Java/11.0.14
Host: localhost:8000
Accept: text/html, image/gif, image/jpeg, *; q=.2, */*; q=.2
Connection: keep-alive

Further Analysis

Potential mitigations include, leveraging SnakeYaml's SafeConstructor while parsing untrusted content.

See https://bitbucket.org/snakeyaml/snakeyaml/issues/561/cve-2022-1471-vulnerability-in#comment-64581479 for discussion on the subject.

Timeline

Date reported: 4/11/2022 Date fixed: 30/12/2022 Date disclosed: 10/13/2022

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`org.yaml:snakeyaml`	all versions	2.0

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.