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CVE-2026-91776 high CVSS 7.5

Vulnerability in com.fasterxml.jackson.core:jackson-databind (CVE-2026-91776)

Summary

Vulnerability in com.fasterxml.jackson.core:jackson-databind (CVE-2026-91776). Risk of unauthorized operations or information disclosure. Exploitable via TypeDeserializerBase._deserializers. Mitigation: upgrade to 2.22.3 or later.

Original description

The description as published by the source.

Summary

With @JsonTypeInfo(use = Id.NAME, defaultImpl = ...), every distinct unknown
raw type ID selects the same fallback deserializer but is retained as a
separate key in TypeDeserializerBase._deserializers. An attacker who can
repeatedly supply new unknown type IDs can grow this process-lifetime cache
without a configured bound.

Details

The affected path is TypeDeserializerBase._findDeserializer(). After an
unknown name-based type ID resolves to the configured fallback/default
implementation, jackson-databind caches the result under the attacker-provided
raw typeId. Although all such IDs select the same fallback deserializer, each
new string remains a distinct cache key.

The behavior is runtime-confirmed in jackson-databind 2.22.1 and 3.2.1.
Current 2.22 and 3.2 source branches retained the unbounded _deserializers
map and per-raw-ID cache write when rechecked. The earlier affected floor has
not been established, patched versions are: 2.18.11, 2.21.7, 2.22.3, 3.1.7 and 3.2.3.

The vulnerable application must enable name-based polymorphism with a
defaultImpl or equivalent fallback, accept attacker-influenced type IDs, and
reuse a long-lived mapper/type deserializer across requests.

Suggested correction: avoid caching each unknown raw ID when every such ID
resolves to the same fallback, use a fallback sentinel, or use an explicitly
bounded concurrency-safe cache. A regression should contrast many distinct
unknown IDs with repetitions of one unknown I…

Source: NIST National Vulnerability Database NVD GitHub Advisory

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-91776 has been found in com.fasterxml.jackson.core:jackson-databind.
Attackers can target a specific entry point like TypeDeserializerBase._deserializers over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 7.5/10.
What to do: upgrade com.fasterxml.jackson.core:jackson-databind to 2.22.3 or later.
If unsure, ask your IT team or search "com.fasterxml.jackson.core:jackson-databind CVE-2026-91776" on the vendor's site.

CVE-2026-91776 (com.fasterxml.jackson.core:jackson-databind) — CWE-400 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: TypeDeserializerBase._deserializers / typeId / _deserializers / defaultImpl
Patched: 2.22.3 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

A vulnerability (CWE-400) exists in com.fasterxml.jackson.core:jackson-databind. Attackers reach the vulnerable code path via TypeDeserializerBase._deserializers without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of com.fasterxml.jackson.core:jackson-databind. Attack surface: TypeDeserializerBase._deserializers / typeId / _deserializers / defaultImpl.

🔥 Severity

Severity: High (CVSS 7.5/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 2.22.3.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    Audit SBOM/dependencies for affected components.

    資産台帳・SBOM・依存マニフェストで com.fasterxml.jackson.core:jackson-databind を使っているサービスとバージョンを洗い出す。

  2. 2
    Apply patch patch 
    Upgrade com.fasterxml.jackson.core:jackson-databind to 2.22.3

    ステージング環境で 2.22.3 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。

  3. 3
    Post-deployment verification verify 
    Confirm patched version is live in production

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

maven com.fasterxml.jackson.core:jackson-databind
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.22.3"}]}]
maven tools.jackson.core:jackson-databind
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.2.3"}]}]

References

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