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GHSA-cxp5-3px4-pw24

HighCVSS 7.5 / 10
Published Sep 30, 2026·Last modified Sep 30, 2026
Affected Components(5)
Maven logocom.fasterxml.jackson.core/jackson-databind
2.22.0 – 2.22.3
Maven logotools.jackson.core/jackson-databind
3.0.0 – 3.1.7
Maven logocom.fasterxml.jackson.core/jackson-databind
2.5.0 – 2.18.11
1 / 2
Description

Summary

When an @JsonIdentityInfo collection or map first creates N unresolved object-ID references and later resolves the same IDs in reverse order, jackson-databind scans the remaining pending-reference accumulator for each resolution. A shallow JSON document whose size grows linearly can therefore cause quadratic CPU work during deserialization.

Details

The affected path is forward-reference completion in CollectionDeserializer.CollectionReferringAccumulator.resolveForwardReference() and the corresponding map implementation. The implementation performs a linear search of the pending accumulator for every resolved object ID.

The behavior is runtime-confirmed in jackson-databind 2.5.0, 2.22.1, and 3.2.1. Current 2.22 and 3.2 source branches retained the same design when rechecked. A 2.4.0 control fails closed before successful reverse-order completion, so 2.5.0 is the conservative runtime-confirmed affected floor. The patched versions are: 2.18.11, 2.21.7, 2.22.3, 3.1.7 and 3.2.3.

The vulnerable application must deserialize attacker-influenced JSON into an identity-enabled collection or map. The issue does not require deep nesting or syntactically unusual JSON.

Suggested correction: replace repeated linear lookup/removal with a keyed pending-reference structure or another design that provides linear or amortized-linear completion. A regression should preserve input order, duplicate-ID behavior, and unresolved-ID errors while bounding reverse-order resolution work.

PoC

The proof constructs a shallow collection containing N unresolved @JsonIdentityInfo references followed by definitions of those same IDs in reverse order. Its ID class counts equals() calls, giving a deterministic work measure rather than a timing-dependent result.

With N=2,000, affected versions perform exactly 2,003,000 ID comparisons. An equally sized control in which every reference is already resolved performs zero comparisons in the pending-reference lookup path. The run is bounded to a 512 MiB JVM. The result demonstrates quadratic growth: approximately N * (N + 1) / 2 comparisons, plus fixed setup comparisons.

Impact

An unauthenticated source that can submit JSON to an application using the affected identity-enabled collection or map shape can consume quadratic CPU and exhaust a request-time or worker-capacity budget, causing denial of service. The application model/configuration prerequisite is material. No confidentiality, integrity, code-execution, or parser-depth impact is claimed.

Requested credit: Daniel Birtwhistle

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Risk Scores
Base Score
7.5

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a high impact on the availability of the system.

Threat Intelligence
6.9

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS
0.45%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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