It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2023-2026-2067 advisory.

    The non-blocking (asynchronous) JSON parser in jackson-core does not enforce the maxNumberLength     constraint defined in StreamReadConstraints (default: 1000 characters). An attacker able to submit JSON to     an application that uses the async parser API can supply a number token of arbitrary length, leading to     excessive memory allocation and potential CPU exhaustion, resulting in a denial of service.



    The synchronous parser enforces this limit correctly, so the constraint is applied inconsistently     depending on which parsing API the application uses.



    Root cause: the async parsing path in NonBlockingUtf8JsonParserBase and related classes never invokes the     number length validation methods. Number parsing methods such as _finishNumberIntegralPart() accumulate     digits into the TextBuffer without any length check, then call _valueComplete() to finalize the token.
    _valueComplete() does not call resetInt() or resetFloat(), which are the methods in ParserBase where     validateIntegerLength() and validateFPLength() are performed. Because that validation step is skipped,     maxNumberLength is never enforced on the async code path.



    Impact: an attacker sending a JSON document containing an arbitrarily long number to an application using     the async parser (for example a Spring WebFlux or other reactive application) can cause unbounded     allocation in the TextBuffer and an OutOfMemoryError. If the application subsequently calls     getBigIntegerValue() or getDecimalValue(), the JVM may additionally be tied up in O(n^2) BigInteger     parsing, causing CPU-based denial of service.



    No privileges or user interaction beyond the ability to submit data for parsing are required.



    This issue affects com.fasterxml.jackson.core:jackson-core from version 2.15.0 through 2.18.5 and from     2.19.0 through 2.21.0, and tools.jackson.core:jackson-core from 3.0.0 through 3.0.x.



    Versions prior to 2.15.0 are not affected, because StreamReadConstraints -- which defines the     maxNumberLength setting -- was first introduced in jackson-core 2.15.0, so no such constraint exists to be     bypassed in earlier releases. Note that GHSA-72hv-8253-57qq records the lower bound of the affected 2.x     range as 2.0.0. (CVE-2026-18401)

    The fix released in jackson-core 2.18.6 and 2.21.1 for CVE-2026-18401 (GHSA-72hv-8253-57qq, number length     constraint bypass in the non-blocking parser) is incomplete. This record covers the remaining bypass.



    The earlier fix wired validateIntegerLength() into a new _setIntLength() helper and invoked it wherever     the integer portion of a number is decided: a terminator byte arrives, a . or e/E is seen, or input ends     inside a fully buffered value. It was not invoked on the attacker-relevant path where the parser runs out     of input while still inside the MINOR_NUMBER_INTEGER_DIGITS minor state and returns NOT_AVAILABLE to the     caller.



    As a result, an attacker who streams JSON to a non-blocking parser in many small chunks, without ever     sending a terminator byte, keeps the parser inside MINOR_NUMBER_INTEGER_DIGITS indefinitely.
    _textBuffer.expandCurrentSegment() grows the accumulator on every chunk while validateIntegerLength() is     never called. The accumulator is bounded only by maxStringLength (20 MiB by default) rather than by     maxNumberLength (1000 by default), an amplification of roughly 20,000x over the documented limit. Because     Java char values occupy two bytes, a single connection can be driven to approximately 40 MiB of heap     before the validator finally fires when the value completes.



    The equivalent fraction-path code is correct: _finishFloatFraction() calls _setFractLength() before its     NOT_AVAILABLE return. The missing call affects the integer-digit paths in _startPositiveNumber(),
    _startNegativeNumber() and _finishNumberIntegralPart() in NonBlockingUtf8JsonParserBase.



    Impact: reactive frameworks such as Spring WebFlux/Reactor, Quarkus, Helidon and Vert.x feed inbound HTTP     or gRPC bytes to the async parser as they arrive, which is precisely the chunked-feed shape required.
    Operators who set StreamReadConstraints.maxNumberLength expecting it to cap memory per number value do not     get that guarantee; memory accumulates per concurrent connection and attacker-controlled concurrency can     exhaust the JVM heap. The synchronous parsers (UTF8StreamJsonParser, ReaderBasedJsonParser) and the async     parser operating on complete input are not affected.



    Exploitation requires only the ability to stream data to a parsing endpoint; no privileges or user     interaction are needed.



    This issue affects com.fasterxml.jackson.core:jackson-core from version 2.15.0 through 2.18.7, from 2.19.0     through 2.21.3, and from 2.22.0 through 2.22.0, and tools.jackson.core:jackson-core from 3.0.0 through     3.1.3 and from 3.2.0 through 3.2.0. Versions prior to 2.15.0 are not affected, because     StreamReadConstraints -- which defines the maxNumberLength setting -- was first introduced in jackson-core     2.15.0, so no such constraint exists to be bypassed in earlier releases. Note that GHSA-r7wm-3cxj-wff9     states the affected 2.x range without a lower bound. (CVE-2026-68494)

Tenable has extracted the preceding description block directly from the tested product security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

Detections

Analytics

Amazon Linux 2023 : jackson-core (ALAS2023-2026-2067)

high Nessus Plugin ID 337219

Version 1.2