CVE-2026-68494 (GCVE-0-2026-68494)

Vulnerability from cvelistv5 – Published: 2026-08-04 14:39 – Updated: 2026-08-05 01:39 X_Open Source
VLAI
Title
jackson-core: Async parser maxNumberLength bypass via chunked digit accumulation (incomplete fix for CVE-2026-18401 / GHSA-72hv-8253-57qq)
Summary
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).
Severity
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
SSVC
Exploitation: poc Automatable: yes Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
  • CWE-770 - Allocation of Resources Without Limits or Throttling
Assigner
References
Impacted products
Vendor Product Version
FasterXML jackson-core Affected: 2.15.0 , < 2.18.8 (maven)
Unaffected: 2.18.8 (maven)
Affected: 2.19.0 , < 2.21.4 (maven)
Unaffected: 2.21.4 (maven)
Create a notification for this product.
FasterXML jackson-core Affected: 3.0.0 , < 3.1.4 (maven)
Unaffected: 3.1.4 (maven)
Create a notification for this product.
Credits
tonghuaroot tonghuaroot cowtowncoder (Tatu Saloranta)
Show details on NVD website
To clipboard 

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    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-68494\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"poc\"}, {\"Automatable\": \"yes\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-08-04T17:53:50.672098Z\"}}}], \"references\": [{\"url\": \"https://github.com/FasterXML/jackson-core/security/advisories/GHSA-r7wm-3cxj-wff9\", \"tags\": [\"exploit\"]}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-08-04T17:54:23.935Z\"}}], \"cna\": {\"tags\": [\"x_open-source\"], \"title\": \"jackson-core: Async parser maxNumberLength bypass via chunked digit accumulation (incomplete fix for CVE-2026-18401 / GHSA-72hv-8253-57qq)\", \"source\": {\"advisory\": \"GHSA-r7wm-3cxj-wff9\", \"discovery\": \"EXTERNAL\"}, \"credits\": [{\"lang\": \"en\", \"type\": \"reporter\", \"value\": \"tonghuaroot\"}, {\"lang\": \"en\", \"type\": \"remediation developer\", \"value\": \"tonghuaroot\"}, {\"lang\": \"en\", \"type\": \"coordinator\", \"value\": \"cowtowncoder (Tatu Saloranta)\"}], \"impacts\": [{\"capecId\": \"CAPEC-130\", \"descriptions\": [{\"lang\": \"en\", \"value\": \"CAPEC-130 Excessive Allocation\"}]}], \"metrics\": [{\"format\": \"CVSS\", \"cvssV4_0\": {\"version\": \"4.0\", \"baseScore\": 8.7, \"attackVector\": \"NETWORK\", \"baseSeverity\": \"HIGH\", \"vectorString\": \"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\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"LOW\", \"attackRequirements\": \"NONE\", \"privilegesRequired\": \"NONE\", \"subIntegrityImpact\": \"NONE\", \"vulnIntegrityImpact\": \"NONE\", \"subAvailabilityImpact\": \"NONE\", \"vulnAvailabilityImpact\": \"HIGH\", \"subConfidentialityImpact\": \"NONE\", \"vulnConfidentialityImpact\": \"NONE\"}, \"scenarios\": [{\"lang\": \"en\", \"value\": \"Application streams attacker-supplied JSON to the non-blocking parser one network chunk at a time, for example via Jackson2JsonDecoder on the Flux\u003cDataBuffer\u003e streaming-decode path in Spring WebFlux, or any direct use of JsonFactory.createNonBlockingByteArrayParser() / createNonBlockingByteBufferParser().\"}]}], \"affected\": [{\"repo\": \"https://github.com/FasterXML/jackson-core\", \"vendor\": \"FasterXML\", \"product\": \"jackson-core\", \"versions\": [{\"status\": \"affected\", \"version\": \"2.15.0\", \"lessThan\": \"2.18.8\", \"versionType\": \"maven\"}, {\"status\": \"unaffected\", \"version\": \"2.18.8\", \"versionType\": \"maven\"}, {\"status\": \"affected\", \"version\": \"2.19.0\", \"lessThan\": \"2.21.4\", \"versionType\": \"maven\"}, {\"status\": \"unaffected\", \"version\": \"2.21.4\", \"versionType\": \"maven\"}], \"packageName\": \"com.fasterxml.jackson.core:jackson-core\", \"programFiles\": [\"src/main/java/com/fasterxml/jackson/core/json/async/NonBlockingUtf8JsonParserBase.java\"], \"collectionURL\": \"https://repo.maven.apache.org/maven2\", \"defaultStatus\": \"unaffected\", \"programRoutines\": [{\"name\": \"NonBlockingUtf8JsonParserBase._startPositiveNumber\"}, {\"name\": \"NonBlockingUtf8JsonParserBase._startNegativeNumber\"}, {\"name\": \"NonBlockingUtf8JsonParserBase._finishNumberIntegralPart\"}]}, {\"repo\": \"https://github.com/FasterXML/jackson-core\", \"vendor\": \"FasterXML\", \"product\": \"jackson-core\", \"versions\": [{\"status\": \"affected\", \"version\": \"3.0.0\", \"lessThan\": \"3.1.4\", \"versionType\": \"maven\"}, {\"status\": \"unaffected\", \"version\": \"3.1.4\", \"versionType\": \"maven\"}], \"packageName\": \"tools.jackson.core:jackson-core\", \"programFiles\": [\"src/main/java/tools/jackson/core/json/async/NonBlockingUtf8JsonParserBase.java\"], \"collectionURL\": \"https://repo.maven.apache.org/maven2\", \"defaultStatus\": \"unaffected\", \"programRoutines\": [{\"name\": \"NonBlockingUtf8JsonParserBase._startPositiveNumber\"}, {\"name\": \"NonBlockingUtf8JsonParserBase._startNegativeNumber\"}, {\"name\": \"NonBlockingUtf8JsonParserBase._finishNumberIntegralPart\"}]}], \"timeline\": [{\"lang\": \"en\", \"time\": \"2026-05-20T22:33:50.000Z\", \"value\": \"Fix merged upstream via FasterXML/jackson-core#1611 (milestone 2.18.8)\"}, {\"lang\": \"en\", \"time\": \"2026-07-10T00:00:00.000Z\", \"value\": \"GHSA-r7wm-3cxj-wff9 published by the maintainer in FasterXML/jackson-core\"}, {\"lang\": \"en\", \"time\": \"2026-07-21T00:00:00.000Z\", \"value\": \"Advisory reviewed and published to the GitHub Advisory Database\"}], \"references\": [{\"url\": \"https://github.com/FasterXML/jackson-core/security/advisories/GHSA-r7wm-3cxj-wff9\", \"name\": \"GHSA-r7wm-3cxj-wff9\", \"tags\": [\"vendor-advisory\"]}, {\"url\": \"https://github.com/FasterXML/jackson-core/pull/1611\", \"name\": \"FasterXML/jackson-core#1611 - Apply number-length validator on streaming integer path of async parser\", \"tags\": [\"patch\"]}, {\"url\": \"https://github.com/FasterXML/jackson-core/commit/050b429804dce2a7e08f0be1b0b4c3d040fdb9cd\", \"name\": \"FasterXML/jackson-core@050b429\", \"tags\": [\"patch\"]}, {\"url\": \"https://github.com/FasterXML/jackson-core/commit/4cdd529749da396cc7edf6d4a2aad41d47902641\", \"name\": \"FasterXML/jackson-core@4cdd529\", \"tags\": [\"patch\"]}, {\"url\": \"https://github.com/FasterXML/jackson-core/commit/c5941e5aae7fd5aeac55d66933cfb82b9aabeef8\", \"name\": \"FasterXML/jackson-core@c5941e5\", \"tags\": [\"patch\"]}, {\"url\": \"https://www.cve.org/CVERecord?id=CVE-2026-18401\", \"name\": \"CVE-2026-18401 - original issue for which this is an incomplete fix\", \"tags\": [\"related\"]}, {\"url\": \"https://github.com/advisories/GHSA-72hv-8253-57qq\", \"name\": \"GHSA-72hv-8253-57qq - original advisory for which this is an incomplete fix\", \"tags\": [\"related\"]}], \"x_generator\": {\"engine\": \"Vulnogram 0.5.0\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"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.\\n\\nThe 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 \u0027.\u0027 or \u0027e\u0027/\u0027E\u0027 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.\\n\\nAs 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.\\n\\nThe 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.\\n\\nImpact: 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.\\n\\nExploitation requires only the ability to stream data to a parsing endpoint; no privileges or user interaction are needed.\\n\\nThis 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).\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"\u003cp\u003eThe fix released in jackson-core 2.18.6 and 2.21.1 for \u003cb\u003eCVE-2026-18401\u003c/b\u003e (GHSA-72hv-8253-57qq, number length constraint bypass in the non-blocking parser) is incomplete. This record covers the remaining bypass.\u003c/p\u003e\u003cp\u003eThe earlier fix wired \u003ctt\u003evalidateIntegerLength()\u003c/tt\u003e into a new \u003ctt\u003e_setIntLength()\u003c/tt\u003e helper and invoked it wherever the integer portion of a number is \u003ci\u003edecided\u003c/i\u003e: a terminator byte arrives, a \u003ctt\u003e.\u003c/tt\u003e or \u003ctt\u003ee\u003c/tt\u003e/\u003ctt\u003eE\u003c/tt\u003e 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 \u003ctt\u003eMINOR_NUMBER_INTEGER_DIGITS\u003c/tt\u003e minor state and returns \u003ctt\u003eNOT_AVAILABLE\u003c/tt\u003e to the caller.\u003c/p\u003e\u003cp\u003eAs 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 \u003ctt\u003eMINOR_NUMBER_INTEGER_DIGITS\u003c/tt\u003e indefinitely. \u003ctt\u003e_textBuffer.expandCurrentSegment()\u003c/tt\u003e grows the accumulator on every chunk while \u003ctt\u003evalidateIntegerLength()\u003c/tt\u003e is never called. The accumulator is bounded only by \u003ctt\u003emaxStringLength\u003c/tt\u003e (20 MiB by default) rather than by \u003ctt\u003emaxNumberLength\u003c/tt\u003e (1000 by default), an amplification of roughly 20,000x over the documented limit. Because Java \u003ctt\u003echar\u003c/tt\u003e 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.\u003c/p\u003e\u003cp\u003eThe equivalent fraction-path code is correct: \u003ctt\u003e_finishFloatFraction()\u003c/tt\u003e calls \u003ctt\u003e_setFractLength()\u003c/tt\u003e before its \u003ctt\u003eNOT_AVAILABLE\u003c/tt\u003e return. The missing call affects the integer-digit paths in \u003ctt\u003e_startPositiveNumber()\u003c/tt\u003e, \u003ctt\u003e_startNegativeNumber()\u003c/tt\u003e and \u003ctt\u003e_finishNumberIntegralPart()\u003c/tt\u003e in \u003ctt\u003eNonBlockingUtf8JsonParserBase\u003c/tt\u003e.\u003c/p\u003e\u003cp\u003e\u003cb\u003eImpact:\u003c/b\u003e 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 \u003ctt\u003eStreamReadConstraints.maxNumberLength\u003c/tt\u003e 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 (\u003ctt\u003eUTF8StreamJsonParser\u003c/tt\u003e, \u003ctt\u003eReaderBasedJsonParser\u003c/tt\u003e) and the async parser operating on complete input are not affected.\u003c/p\u003e\u003cp\u003eExploitation requires only the ability to stream data to a parsing endpoint; no privileges or user interaction are needed.\u003c/p\u003e\u003cp\u003eThis issue affects \u003ctt\u003ecom.fasterxml.jackson.core:jackson-core\u003c/tt\u003e from version 2.15.0 through 2.18.7, and from 2.19.0 through 2.21.3, and \u003ctt\u003etools.jackson.core:jackson-core\u003c/tt\u003e from 3.0.0 through 3.1.3. Versions prior to 2.15.0 are not affected, because \u003ctt\u003eStreamReadConstraints\u003c/tt\u003e -- which defines the \u003ctt\u003emaxNumberLength\u003c/tt\u003e 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.\u003c/p\u003e\u003cp\u003eThe 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).\u003c/p\u003e\", \"base64\": false}]}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-770\", \"description\": \"CWE-770 Allocation of Resources Without Limits or Throttling\"}]}], \"providerMetadata\": {\"orgId\": \"36c7be3b-2937-45df-85ea-ca7133ea542c\", \"shortName\": \"HeroDevs\", \"dateUpdated\": \"2026-08-05T01:39:56.955Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-68494\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-08-05T01:39:56.955Z\", \"dateReserved\": \"2026-07-30T15:20:37.472Z\", \"assignerOrgId\": \"36c7be3b-2937-45df-85ea-ca7133ea542c\", \"datePublished\": \"2026-08-04T14:39:14.471Z\", \"assignerShortName\": \"HeroDevs\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.