---
id: CVE-2026-91777
title: >-
  Forward-reference completion for @JsonIdentityInfo object IDs in FasterXML
  jackson-databind performs a linear scan of the pending-reference accumulator
  for every resolved ID
summary: >-
  Forward-reference completion for @JsonIdentityInfo object IDs in FasterXML
  jackson-databind performs a linear scan of the pending-reference accumulator
  for every resolved ID. The affected paths are
  CollectionDeserializer.CollectionReferr…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-400
vendor: FasterXML
product: 'com.fasterxml.jackson.core:jackson-databind'
affected:
  - 'com.fasterxml.jackson.core:jackson-databind >= 2.5.0 <= 2.18.10'
  - 'com.fasterxml.jackson.core:jackson-databind >= 2.19.0 <= 2.21.6'
  - 'com.fasterxml.jackson.core:jackson-databind >= 2.22.0 <= 2.22.2'
  - 'tools.jackson.core:jackson-databind >= 3.0.0 <= 3.1.6'
  - 'tools.jackson.core:jackson-databind >= 3.2.0 <= 3.2.2'
published: '2026-09-23'
updated: '2026-09-24'
sourceUpdated: '2026-09-24T20:43:32.537'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-91777'
references:
  - url: 'https://github.com/FasterXML/jackson-databind/issues/6204'
    label: 36c7be3b-2937-45df-85ea-ca7133ea542c
  - url: >-
      https://github.com/FasterXML/jackson-databind/security/advisories/GHSA-cxp5-3px4-pw24
    label: 36c7be3b-2937-45df-85ea-ca7133ea542c
  - url: >-
      https://github.com/FasterXML/jackson-databind/security/advisories/GHSA-cxp5-3px4-pw24
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
tags:
  - nvd
  - cve.org
  - exploit-available
epss: 0.0045
epssPercentile: 0.36408
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-09-23T14:04:51.226591Z'
ingestedAt: '2026-09-23T03:16:01.009Z'
---

## Overview

Forward-reference completion for @JsonIdentityInfo object IDs in FasterXML jackson-databind performs a linear scan of the pending-reference accumulator for every resolved ID. The affected paths are CollectionDeserializer.CollectionReferringAccumulator.resolveForwardReference() and the equivalent implementation in MapDeserializer. When a document first creates N unresolved object-ID references in an identity-enabled collection or map and then defines those same IDs in reverse order, completion performs on the order of N * (N + 1) / 2 identity comparisons, so a shallow document whose size grows linearly causes quadratic CPU work during deserialization. The reporter instrumented equals() calls on the ID class and measured exactly 2,003,000 comparisons at N = 2,000, against zero comparisons in the pending-reference lookup path for an equally sized control in which every reference was already resolved. The input requires no deep nesting and no syntactically unusual JSON. Exploitation requires an application that deserializes attacker-influenced JSON into an identity-enabled collection or map. The fix replaces the repeated linear lookup with a keyed pending-reference structure.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.