CVE-2026-89425: DoS (CVSS 7.5)

Description

UTF8DataInputJsonParser._reportInvalidToken() in FasterXML jackson-core builds the offending-token text for its error message by appending Java identifier characters to a StringBuilder in a loop that has no upper bound. Unlike the three sibling parser implementations, including UTF8StreamJsonParser, it never consults ErrorReportConfiguration.getMaxErrorTokenLength() (default 256). A malformed token supplied to a parser created through JsonFactory.createParser(DataInput) is therefore accumulated in full. No StreamReadConstraints setting mitigates this: maxDocumentLength cannot be applied to DataInput sources at all, and maxStringLength does not cover this path because the accumulation bypasses ReadConstrainedTextBuffer. The reporter measured a 20,000,109-character exception message from a 20-million-character malformed token on the DataInput path, against 367 characters for identical input on the InputStream path. Scaling the payload drives the StringBuilder, which also incurs byte-to-char expansion and internal array doubling, to many times the raw payload size and can trigger OutOfMemoryError for the whole JVM. UTF8DataInputJsonParser was introduced in 2.8.0 together with createParser(DataInput); releases before 2.8.0 do not contain the affected class.

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CVSS v3.1 Score

7.5

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS — Exploit Prediction

0.0049

Probability of exploitation

0.40%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-400 Uncontrolled Resource Consumption

CWE-770 CWE-770

References

Other References

https://github.com/FasterXML/jackson-core/pull/1698 https://github.com/FasterXML/jackson-core/security/advisories/GHSA-7hhh-6rmp-j9qf https://github.com/FasterXML/jackson-core/security/advisories/GHSA-7hhh-6rmp-j9qf

Frequently Asked Questions

What is CVE-2026-89425? +

UTF8DataInputJsonParser._reportInvalidToken() in FasterXML jackson-core builds the offending-token text for its error message by appending Java identifier characters to a StringBuilder in a loop that has no upper bound. Unlike the three sibling parser implementations, including UTF8StreamJsonParser, it never consults ErrorReportConfiguration.getMaxErrorTokenLength() (default 256). A malformed token supplied to a parser created through JsonFactory.createParser(DataInput) is therefore accumulated in full. No StreamReadConstraints setting mitigates this: maxDocumentLength cannot be applied to DataInput sources at all, and maxStringLength does not cover this path because the accumulation bypasses ReadConstrainedTextBuffer. The reporter measured a 20,000,109-character exception message from a 20-million-character malformed token on the DataInput path, against 367 characters for identical input on the InputStream path. Scaling the payload drives the StringBuilder, which also incurs byte-to-char expansion and internal array doubling, to many times the raw payload size and can trigger OutOfMemoryError for the whole JVM. UTF8DataInputJsonParser was introduced in 2.8.0 together with createParser(DataInput); releases before 2.8.0 do not contain the affected class. It has a CVSS v3.1 base score of 7.5 (HIGH).

How severe is CVE-2026-89425? +

CVE-2026-89425 has a CVSS v3.1 score of 7.5 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0049, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-89425? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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