CVE-2026-91777

jackson-databind: quadratic forward-reference completion in Collection and Map deserializers

CVSS 3.1 7.5 HIGHCheck source for fixed versionsKEV status unknown

Original advisory

cve-program · CVE-2026-91777

Published

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.

Read the publisher's advisory

Affected versions, risk and source history

cve-program · CVE-2026-91777

Published

com.fasterxml.jackson.core:jackson-databind

https://repo1.maven.org/maven2

Publisher's version information

Shown as published. These rules are not interpreted as NuGet package version ranges.

{
                    "vendor": "FasterXML",
                    "product": "jackson-databind",
                    "collectionURL": "https://repo1.maven.org/maven2",
                    "packageName": "com.fasterxml.jackson.core:jackson-databind",
                    "repo": "https://github.com/FasterXML/jackson-databind",
                    "programRoutines": [
                        {
                            "name": "com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.CollectionReferringAccumulator.resolveForwardReference"
                        },
                        {
                            "name": "com.fasterxml.jackson.databind.deser.std.MapDeserializer.MapReferringAccumulator.resolveForwardReference"
                        }
                    ],
                    "versions": [
                        {
                            "status": "affected",
                            "version": "2.5.0",
                            "lessThanOrEqual": "2.18.10",
                            "versionType": "maven"
                        },
                        {
                            "status": "affected",
                            "version": "2.19.0",
                            "lessThanOrEqual": "2.21.6",
                            "versionType": "maven"
                        },
                        {
                            "status": "affected",
                            "version": "2.22.0",
                            "lessThanOrEqual": "2.22.2",
                            "versionType": "maven"
                        }
                    ],
                    "defaultStatus": "unaffected"
                }

tools.jackson.core:jackson-databind

https://repo1.maven.org/maven2

Publisher's version information

Shown as published. These rules are not interpreted as NuGet package version ranges.

{
                    "vendor": "FasterXML",
                    "product": "jackson-databind",
                    "collectionURL": "https://repo1.maven.org/maven2",
                    "packageName": "tools.jackson.core:jackson-databind",
                    "repo": "https://github.com/FasterXML/jackson-databind",
                    "programRoutines": [
                        {
                            "name": "tools.jackson.databind.deser.jdk.CollectionDeserializer.CollectionReferringAccumulator.resolveForwardReference"
                        },
                        {
                            "name": "tools.jackson.databind.deser.jdk.MapDeserializer.MapReferringAccumulator.resolveForwardReference"
                        }
                    ],
                    "versions": [
                        {
                            "status": "affected",
                            "version": "3.0.0",
                            "lessThanOrEqual": "3.1.6",
                            "versionType": "maven"
                        },
                        {
                            "status": "affected",
                            "version": "3.2.0",
                            "lessThanOrEqual": "3.2.2",
                            "versionType": "maven"
                        }
                    ],
                    "defaultStatus": "unaffected"
                }

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