Deskripsi CVE

jackson-core: Async parser maxNumberLength bypass via chunked digit accumulation (incomplete fix for CVE-2026-18401 / GHSA-72hv-8253-57qq)

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, and from 2.19.0 through 2.21.3, and tools.jackson.core:jackson-core from 3.0.0 through 3.1.3. 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. The 2.22.x and 3.2.x release lines are not affected: those branches were created after the fix commit landed on 2026-05-21 and therefore contain it from their initial releases (2.22.0, tagged 2026-06-03, and 3.2.0, tagged 2026-06-08).

Informasi CVE

Kelemahan Terkait

CWE-ID	Nama Kelemahan	Sumber
CWE-770	Allocation of Resources Without Limits or Throttling The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.

Metrik

Metrik	Skor	Tingkat keparahan	CVSS Vektor	Sumber
V4.0	8.7	HIGH	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N Informasi lebih lanjut Base: Exploitabilty Metrics The Exploitability metrics reflect the characteristics of the “thing that is vulnerable”, which we refer to formally as the vulnerable system. Attack Vector This metric reflects the context by which vulnerability exploitation is possible. Network The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers). Attack Complexity This metric captures measurable actions that must be taken by the attacker to actively evade or circumvent existing built-in security-enhancing conditions in order to obtain a working exploit. Low The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system. Attack Requirements This metric captures the prerequisite deployment and execution conditions or variables of the vulnerable system that enable the attack. None The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability. Privileges Required This metric describes the level of privileges an attacker must possess prior to successfully exploiting the vulnerability. None The attacker is unauthenticated prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack. User Interaction This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable system. None The vulnerable system can be exploited without interaction from any human user, other than the attacker. Examples include: a remote attacker is able to send packets to a target system a locally authenticated attacker executes code to elevate privileges Base: Impact Metrics The Impact metrics capture the effects of a successfully exploited vulnerability. Analysts should constrain impacts to a reasonable, final outcome which they are confident an attacker is able to achieve. Confidentiality Impact This metric measures the impact to the confidentiality of the information managed by the system due to a successfully exploited vulnerability. None There is no loss of confidentiality within the Vulnerable System. Integrity Impact This metric measures the impact to integrity of a successfully exploited vulnerability. None There is no loss of integrity within the Vulnerable System. Availability Impact This metric measures the impact to the availability of the impacted system resulting from a successfully exploited vulnerability. High There is a total loss of availability, resulting in the attacker being able to fully deny access to resources in the Vulnerable System; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the Vulnerable System (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable). Sub Confidentiality Impact Negligible There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System. Sub Integrity Impact None There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System. Sub Availability Impact None There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System. Threat Metrics The Threat metrics measure the current state of exploit techniques or code availability for a vulnerability. Environmental Metrics These metrics enable the consumer analyst to customize the resulting score depending on the importance of the affected IT asset to a user’s organization, measured in terms of complementary/alternative security controls in place, Confidentiality, Integrity, and Availability. The metrics are the modified equivalent of Base metrics and are assigned values based on the system placement within organizational infrastructure. Supplemental Metrics Supplemental metric group provides new metrics that describe and measure additional extrinsic attributes of a vulnerability. While the assessment of Supplemental metrics is provisioned by the provider, the usage and response plan of each metric within the Supplemental metric group is determined by the consumer.