CVE-2026-18401 (GCVE-0-2026-18401)

Vulnerability from cvelistv5 – Published: 2026-08-04 14:23 – Updated: 2026-08-04 17:59 X_Open Source
VLAI
Title
jackson-core: Number length constraint bypass in non-blocking (async) JSON parser leads to potential denial of service
Summary
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.
Severity
6.9 (Medium)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
SSVC
Exploitation: poc Automatable: yes Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-04 17:58 UTC
CWE
  • CWE-770 - Allocation of Resources Without Limits or Throttling
Assigner
HeroDevs CNA under the mitre root
CNA scorecard B 82/100 over 17 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
FasterXML jackson-core Affected: 2.15.0 , ≤ 2.18.5 (maven)
Unaffected: 2.18.6 (maven)
Affected: 2.19.0 , < 2.21.1 (maven)
Unaffected: 2.21.1 (maven)
guessed Create a notification for this product.
FasterXML jackson-core Affected: 3.0.0 , < 3.1.0 (maven)
Unaffected: 3.1.0 (maven)
guessed Create a notification for this product.
Credits
sprabhav7 rohan-repos neilmadden-hazelcast awsactran pjfanning (PJ Fanning) cowtowncoder (Tatu Saloranta)
Show details on NVD website
To clipboard 

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            "value": "El analizador JSON no bloqueante (as\u00edncrono) en jackson-core no aplica la restricci\u00f3n maxNumberLength definida en StreamReadConstraints (predeterminado: 1000 caracteres). Un atacante capaz de enviar JSON a una aplicaci\u00f3n que utiliza la API del analizador as\u00edncrono puede proporcionar un token num\u00e9rico de longitud arbitraria, lo que lleva a una asignaci\u00f3n excesiva de memoria y un posible agotamiento de la CPU, resultando en una denegaci\u00f3n de servicio.\n\nEl analizador s\u00edncrono aplica este l\u00edmite correctamente, por lo que la restricci\u00f3n se aplica de forma inconsistente dependiendo de qu\u00e9 API de an\u00e1lisis utilice la aplicaci\u00f3n.\n\nCausa ra\u00edz: la ruta de an\u00e1lisis as\u00edncrono en NonBlockingUtf8JsonParserBase y clases relacionadas nunca invoca los m\u00e9todos de validaci\u00f3n de longitud de n\u00fameros. Los m\u00e9todos de an\u00e1lisis de n\u00fameros como _finishNumberIntegralPart() acumulan d\u00edgitos en el TextBuffer sin ninguna verificaci\u00f3n de longitud, luego llaman a _valueComplete() para finalizar el token. _valueComplete() no llama a resetInt() ni a resetFloat(), que son los m\u00e9todos en ParserBase donde se realizan validateIntegerLength() y validateFPLength(). Debido a que ese paso de validaci\u00f3n se omite, maxNumberLength nunca se aplica en la ruta de c\u00f3digo as\u00edncrono.\n\nImpacto: un atacante que env\u00eda un documento JSON que contiene un n\u00famero arbitrariamente largo a una aplicaci\u00f3n que utiliza el analizador as\u00edncrono (por ejemplo, una aplicaci\u00f3n Spring WebFlux u otra aplicaci\u00f3n reactiva) puede causar una asignaci\u00f3n ilimitada en el TextBuffer y un OutOfMemoryError. Si la aplicaci\u00f3n posteriormente llama a getBigIntegerValue() o getDecimalValue(), la JVM puede adem\u00e1s quedar ocupada en el an\u00e1lisis de BigInteger en O(n^2), causando una denegaci\u00f3n de servicio basada en CPU.\n\nNo se requieren privilegios ni interacci\u00f3n del usuario m\u00e1s all\u00e1 de la capacidad de enviar datos para su an\u00e1lisis.\n\nEste problema afecta a com.fasterxml.jackson.core:jackson-core desde la versi\u00f3n 2.15.0 hasta la 2.18.5 y desde la 2.19.0 hasta la 2.21.0, y a tools.jackson.core:jackson-core desde la 3.0.0 hasta la 3.0.x.\n\nLas versiones anteriores a la 2.15.0 no se ven afectadas, porque StreamReadConstraints -- que define la configuraci\u00f3n maxNumberLength -- se introdujo por primera vez en jackson-core 2.15.0, por lo que no existe tal restricci\u00f3n que pueda ser eludida en versiones anteriores. Tenga en cuenta que GHSA-72hv-8253-57qq registra el l\u00edmite inferior del rango 2.x afectado como 2.0.0."
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        "lastModified": "2026-10-23T23:10:00.157",
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                "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
                "version": "4.0",
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              "source": "36c7be3b-2937-45df-85ea-ca7133ea542c",
              "type": "Secondary"
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          "ssvcV203": [
            {
              "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "ssvcData": {
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                "options": [
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                "timestamp": "2026-08-04T17:58:30.797291Z",
                "version": "2.0.3"
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            "url": "https://github.com/FasterXML/jackson-core/commit/b0c428e6f993e1b5ece5c1c3cb2523e887cd52cf"
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            "source": "36c7be3b-2937-45df-85ea-ca7133ea542c",
            "url": "https://github.com/FasterXML/jackson-core/security/advisories/GHSA-72hv-8253-57qq"
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            "url": "https://github.com/FasterXML/jackson-core/security/advisories/GHSA-72hv-8253-57qq"
          }
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        "vulnStatus": "Awaiting Analysis",
        "weaknesses": [
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            "description": [
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                "lang": "en",
                "value": "CWE-770"
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            ],
            "source": "36c7be3b-2937-45df-85ea-ca7133ea542c",
            "type": "Secondary"
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        ]
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    },
    "redhat_vex": {
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      "current_release_date": "2026-08-10T12:45:54+00:00",
      "cve": "CVE-2026-18401",
      "id": "CVE-2026-18401",
      "initial_release_date": "2026-08-04T14:23:27.174000+00:00",
      "product_status:known_affected": "76",
      "product_status:known_not_affected": "96",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "tools.jackson.core/jackson-core: com.fasterxml.jackson.core/jackson-core: jackson-core: Denial of Service due to number length bypass in asynchronous JSON parser",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-18401.json",
      "version": "3"
    },
    "vulnrichment": {
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              {
                "other": {
                  "content": {
                    "id": "CVE-2026-18401",
                    "options": [
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                    "role": "CISA Coordinator",
                    "timestamp": "2026-08-04T17:58:30.797291Z",
                    "version": "2.0.3"
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            "providerMetadata": {
              "dateUpdated": "2026-08-04T17:58:52.981Z",
              "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "shortName": "CISA-ADP"
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                "url": "https://github.com/FasterXML/jackson-core/security/advisories/GHSA-72hv-8253-57qq"
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            "title": "CISA ADP Vulnrichment"
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        "cna": {
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              "collectionURL": "https://repo.maven.apache.org/maven2",
              "defaultStatus": "unaffected",
              "packageName": "com.fasterxml.jackson.core:jackson-core",
              "product": "jackson-core",
              "programFiles": [
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              "programRoutines": [
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                  "name": "NonBlockingUtf8JsonParserBase._finishNumberIntegralPart"
                },
                {
                  "name": "NonBlockingUtf8JsonParserBase._valueComplete"
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              ],
              "repo": "https://github.com/FasterXML/jackson-core",
              "vendor": "FasterXML",
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                  "status": "affected",
                  "version": "2.15.0",
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                  "version": "2.18.6",
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                  "version": "2.19.0",
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              "type": "finder",
              "value": "sprabhav7"
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            {
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              "type": "finder",
              "value": "rohan-repos"
            },
            {
              "lang": "en",
              "type": "analyst",
              "value": "neilmadden-hazelcast"
            },
            {
              "lang": "en",
              "type": "analyst",
              "value": "awsactran"
            },
            {
              "lang": "en",
              "type": "remediation developer",
              "value": "pjfanning (PJ Fanning)"
            },
            {
              "lang": "en",
              "type": "coordinator",
              "value": "cowtowncoder (Tatu Saloranta)"
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                  "value": "\u003cp\u003eThe 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.\u003c/p\u003e\u003cp\u003eThe synchronous parser enforces this limit correctly, so the constraint is applied inconsistently depending on which parsing API the application uses.\u003c/p\u003e\u003cp\u003e\u003cb\u003eRoot cause:\u003c/b\u003e 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.\u003c/p\u003e\u003cp\u003e\u003cb\u003eImpact:\u003c/b\u003e 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.\u003c/p\u003e\u003cp\u003eNo privileges or user interaction beyond the ability to submit data for parsing are required.\u003c/p\u003e\u003cp\u003eThis 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.\u003c/p\u003e\u003cp\u003eVersions 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.\u003c/p\u003e"
                }
              ],
              "value": "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.\n\n\n\nThe synchronous parser enforces this limit correctly, so the constraint is applied inconsistently depending on which parsing API the application uses.\n\n\n\nRoot 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.\n\n\n\nImpact: 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.\n\n\n\nNo privileges or user interaction beyond the ability to submit data for parsing are required.\n\n\n\nThis 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.\n\n\n\nVersions 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."
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                "Recovery": "NOT_DEFINED",
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                "exploitMaturity": "NOT_DEFINED",
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                "providerUrgency": "NOT_DEFINED",
                "subAvailabilityImpact": "NONE",
                "subConfidentialityImpact": "NONE",
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                "vulnerabilityResponseEffort": "NOT_DEFINED"
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              "scenarios": [
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              "time": "2026-02-22T20:17:00.000Z",
              "value": "Fix merged upstream via FasterXML/jackson-core#1555 (milestone 2.18.6)"
            },
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              "lang": "en",
              "time": "2026-02-26T00:00:00.000Z",
              "value": "GHSA-72hv-8253-57qq published by the maintainer in FasterXML/jackson-core"
            },
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              "lang": "en",
              "time": "2026-02-28T00:00:00.000Z",
              "value": "Advisory reviewed and published to the GitHub Advisory Database"
            }
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        "cveId": "CVE-2026-18401",
        "datePublished": "2026-08-04T14:23:27.174Z",
        "dateReserved": "2026-07-30T15:20:53.701Z",
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      },
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  }
}



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