Bug 2539285 - CVE-2026-89425 log4j: Jackson-core: Denial of Service via unbounded StringBuilder growth during malformed token processing [fedora-all]
Summary: CVE-2026-89425 log4j: Jackson-core: Denial of Service via unbounded StringBui...
Keywords:
Status: NEW
Alias: None
Product: Fedora
Classification: Fedora
Component: log4j
Version: rawhide
Hardware: Unspecified
OS: Unspecified
high
high
Target Milestone: ---
Assignee: Paul Wouters
QA Contact: Fedora Extras Quality Assurance
URL:
Whiteboard: {"flaws": ["f3774991-148f-42c8-be96-6...
Depends On:
Blocks: CVE-2026-89425
TreeView+ depends on / blocked
 
Reported: 2026-09-23 09:33 UTC by Ganesh
Modified: 2026-09-23 09:33 UTC (History)
7 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed:
Type: ---
Embargoed:


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Description Ganesh 2026-09-23 09:33:36 UTC
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.

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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