CVE-2026-68498 Aplicación tardía de maxNameLength en jackson-core permite denegación de servicio por agotamiento de memoria

Qué es CVE-2026-68498

En jackson-core, StreamReadConstraints.maxNameLength no se aplica mientras se acumula el nombre de una propiedad JSON en los parsers sobre entrada de caracteres (Reader, String o char[], servidos por ReaderBasedJsonParser). Esa ruta reutiliza la verificación de longitud de valores de cadena, mucho mayor por defecto, por lo que un nombre de propiedad extenso puede consumir memoria de forma excesiva y provocar una denegación de servicio.

Productos y versiones afectadas

• FasterXML jackson-core

  • desde 2.16.0 hasta antes de 2.18.10
  • desde 2.19.0 hasta antes de 2.21.6
  • desde 2.22.0 hasta antes de 2.22.2

• FasterXML jackson-core

  • desde 3.0.0 hasta antes de 3.1.6
  • desde 3.2.0 hasta antes de 3.2.2

Qué hacer

1. Verificá si usás jackson-core y en qué versión: el rango afectado figura arriba.
2. Actualizá a la versión corregida que indique el fabricante en su aviso (ver referencias) o aplicá la mitigación que publique.
3. Revisá registros y accesos de los sistemas expuestos para descartar que se haya aprovechado antes de corregir.

Calculadora CVSS

CVSS 3.1 · 7.5 ALTA

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

VECTOR DE ATAQUE (AV)

Red

COMPLEJIDAD DEL ATAQUE (AC)

Baja

PRIVILEGIOS REQUERIDOS (PR)

Ninguno

INTERACCIÓN DEL USUARIO (UI)

Ninguna

ALCANCE (S)

Sin cambio

CONFIDENCIALIDAD (C)

Ninguna

INTEGRIDAD (I)

Ninguna

DISPONIBILIDAD (A)

Alta

Abrir la calculadora completa →

Descripción original

StreamReadConstraints.maxNameLength (default 50,000 characters) is intended to bound how much memory a single JSON Object property name can consume while being parsed, independently of the much larger maxStringLength (default 100,000,000 characters) that bounds ordinary string values. For parsers built over character input — Reader, String or char[] sources, all served by ReaderBasedJsonParser — that bound is not applied while the name is being accumulated. The code path instead re-uses the string-value length check, which is roughly 2000x larger by default. In the character-input slow path, ReaderBasedJsonParser._parseName2() accumulates the name into the TextBuffer and, when a segment fills, calls TextBuffer.finishCurrentSegment(), which validates only maxStringLength. The correct check, StreamReadConstraints.validateNameLength(int), is reached afterwards in CharsToNameCanonicalizer.findSymbol(), once the entire name has been scanned to its closing quote. By that point the full name — up to maxStringLength characters — has already been buffered in memory. A remote attacker who can have a single sufficiently long JSON Object property name parsed through this path can force allocation on the order of 100,000,000 characters (approximately 200 MB, with segment bookkeeping pushing real peak usage higher) before any StreamConstraintsException is thrown, instead of the approximately 50,000-character (about 100 KB) bound the API promises. Repeating this across concurrent requests can exhaust the heap and crash the process. No authentication or user interaction is required. Because StreamReadConstraints.maxDocumentLength is disabled by default (-1), nothing else bounds the token first, so the issue is exploitable under default configuration. Byte-input parsers are not affected: UTF8StreamJsonParser, UTF8DataInputJsonParser and the non-blocking (async) parsers re-validate maxNameLength on every growth of the name-decode buffer via ParserBase._growNameDecodeBuffer(), rejecting an oversized name after allocating only tens of kilobytes. Applications are exposed when untrusted JSON is parsed from a String, Reader or char[] — for example an HTTP request body already read into a String — rather than from raw UTF-8 bytes. This issue affects com.fasterxml.jackson.core:jackson-core from 2.16.0 and tools.jackson.core:jackson-core from 3.0.0. Releases before 2.16.0 are not affected, because StreamReadConstraints.maxNameLength was first introduced in jackson-core 2.16.0.

Referencias

• github.com/FasterXML/jackson-core/security/advisories/GHSA-649p-m576-vr99VENDOR-ADVISORY
• github.com/FasterXML/jackson-core/pull/1643PATCH
• github.com/FasterXML/jackson-core/commit/2cd206de1163e3fcff7bdaca425274f00668b075PATCH
• github.com/FasterXML/jackson-core/blob/2.x/release-notes/VERSION-2.xRELEASE-NOTES
• github.com/FasterXML/jackson-core/blob/3.x/release-notes/VERSIONRELEASE-NOTES

Historial de la alerta

1. 16 OCT · 19:25VULNERABILIDAD Nueva vulnerabilidad detectada.

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