CVE-2025-49128 is a medium-severity (CVSS 4) CWE-209 vulnerability in com.fasterxml.jackson.core:jackson-core. A fix is available for com.fasterxml.jackson.core:jackson-core — see the affected versions and patch details below.
Jackson-core Vulnerable to Memory Disclosure via Source Snippet in JsonLocation
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.
Exploitation and automatability from CISA’s SSVC triage for CVE-2025-49128.
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.
How urgent is this, really
CVE-2025-49128 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,636 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
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 | 2.13.0com.fasterxml.jackson.core:jackson-core: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, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
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 CVE-2025-49128 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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2025-49128 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2025-49128. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2025-49128 in your dependencies?
O3 Security finds CVE-2025-49128 across Maven dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.