Any application creating parsers via JsonFactory.createParser(DataInput) over attacker-supplied input (a fully public, documented API) is exposed to unbounded memory growth from a single malformed token. Scaling the payload from the 20MB demonstrated here to gigabytes (well within a typical unbounded request body) would drive the accumulated StringBuilder — which additionally undergoes byte-to-char expansion and internal doubling — to consume many times the raw payload size, realistically triggering OutOfMemoryError and denying …
Any application that coerces a String-typed JSON field to a number (default jackson-databind behavior) is exposed: an attacker who can submit a large numeric-looking string (up to maxStringLength's default of 20,000,000 characters — far larger than needed given the measured curve) can pin a request-handling thread for an extended period with a single request. Because the cost scales quadratically, a handful of concurrent moderately-sized requests (tens to low hundreds of …
The fix released in jackson-core 2.18.6 and 2.21.1 for GHSA-72hv-8253-57qq (Number Length Constraint Bypass in Async Parser, published 2026-02-28) is incomplete. The fix commit b0c428e6 (#1555) wired validateIntegerLength into a new _setIntLength helper and called it at every place where the integer portion of a number is decided (terminator byte arrived, . / e/E seen, end-of-feed inside a fully-buffered value). It did not call it on the much more attacker-relevant …
Jackson Core 3.x does not consistently enforce StreamReadConstraints.maxDocumentLength. Oversized JSON documents can be accepted without a StreamConstraintsException in multiple parser entry points, which allows configured size limits to be bypassed and weakens denial-of-service protections.
The UTF8DataInputJsonParser, which is used when parsing from a java.io.DataInput source, bypasses the maxNestingDepth constraint (default: 500) defined in StreamReadConstraints. A similar issue was found in ReaderBasedJsonParser. This allows a user to supply a JSON document with excessive nesting, which can cause a StackOverflowError when the structure is processed, leading to a Denial of Service (DoS). The related fix for com.fasterxml.jackson.core:jackson-core, CVE-2025-52999, was not fully applied to tools.jackson.core:jackson-core until the …
The non-blocking (async) JSON parser in jackson-core bypasses the maxNumberLength constraint (default: 1000 characters) defined in StreamReadConstraints. This allows an attacker to send JSON with arbitrarily long numbers through the async parser API, leading to excessive memory allocation and potential CPU exhaustion, resulting in a Denial of Service (DoS). The standard synchronous parser correctly enforces this limit, but the async parser fails to do so, creating an inconsistent enforcement policy.