GHSA-wf8f-6423-gfxg
MEDIUMJackson-core Vulnerable to Memory Disclosure via Source Snippet in JsonLocation
EPSS Exploitation Probability
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.
Blast Radius
com.fasterxml.jackson.core:jackson-coreReal-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
Overview
A flaw in Jackson-core's JsonLocation._appendSourceDesc method allows up to 500 bytes of unintended memory content to be included in exception messages. When parsing JSON from a byte array with an offset and length, the exception message incorrectly reads from the beginning of the array instead of the logical payload start. This results in possible information disclosure in systems using pooled or reused buffers, like Netty or Vert.x.
Details
The vulnerability affects the creation of exception messages like:
JsonParseException: Unexpected character ... at [Source: (byte[])...]
When JsonFactory.createParser(byte[] data, int offset, int len) is used, and an error occurs while parsing, the exception message should include a snippet from the specified logical payload. However, the method _appendSourceDesc ignores the offset, and always starts reading from index 0.
If the buffer contains residual sensitive data from a previous request, such as credentials or document contents, that data may be exposed if the exception is propagated to the client.
The issue particularly impacts server applications using:
- Pooled byte buffers (e.g., Netty)
- Frameworks that surface parse errors in HTTP responses
- Default Jackson settings (i.e.,
INCLUDE_SOURCE_IN_LOCATIONis enabled)
A documented real-world example is CVE-2021-22145 in Elasticsearch, which stemmed from the same root cause.
Attack Scenario
An attacker sends malformed JSON to a service using Jackson and pooled byte buffers (e.g., Netty-based HTTP servers). If the server reuses a buffer and includes the parser’s exception in its HTTP 400 response, the attacker may receive residual data from previous requests.
Proof of Concept
byte[] buffer = new byte[1000];
System.arraycopy("SECRET".getBytes(), 0, buffer, 0, 6);
System.arraycopy("{ \"bad\": }".getBytes(), 0, buffer, 700, 10);
JsonFactory factory = new JsonFactory();
JsonParser parser = factory.createParser(buffer, 700, 20);
parser.nextToken(); // throws exception
// Exception message will include "SECRET"
Patches
This issue was silently fixed in jackson-core version 2.13.0, released on September 30, 2021, via PR #652.
All users should upgrade to version 2.13.0 or later.
Workarounds
If upgrading is not immediately possible, applications can mitigate the issue by:
-
Disabling exception message exposure to clients — avoid returning parsing exception messages in HTTP responses.
-
Disabling source inclusion in exceptions by setting:
jsonFactory.disable(JsonFactory.Feature.INCLUDE_SOURCE_IN_LOCATION);This prevents Jackson from embedding any source content in exception messages, avoiding leakage.
References
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | com.fasterxml.jackson.core:jackson-core | ≥ 2.0.0&&< 2.13.0 | 2.13.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for com.fasterxml.jackson.core:jackson-core. 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.
Fix
Update com.fasterxml.jackson.core:jackson-core to 2.13.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-wf8f-6423-gfxg is resolved across your whole dependency graph.
Workarounds
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 O3 protects you
O3 pinpoints whether GHSA-wf8f-6423-gfxg is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-wf8f-6423-gfxg. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-wf8f-6423-gfxg in your dependencies?
O3 detects GHSA-wf8f-6423-gfxg across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.