CVE-2026-89425

Summary

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.

Affected Software

Weaknesses

• CWE-770: CWE-770 Allocation of Resources Without Limits or Throttling
• CWE-400: CWE-400 Uncontrolled Resource Consumption

Workarounds

No StreamReadConstraints or ErrorReportConfiguration setting mitigates this issue on the affected code path. Where possible, avoid JsonFactory.createParser(DataInput) for attacker-supplied content and use createParser(InputStream), createParser(Reader) or a byte-array overload instead; those parser implementations enforce maxErrorTokenLength correctly. Otherwise, bound input size ahead of the parser and cap JVM heap so that a single request cannot exhaust process memory.

References

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

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