Vulnerability in com.cedarpolicy:cedar-java (CVE-2026-55772)
Summary
Vulnerability in com.cedarpolicy:cedar-java (CVE-2026-55772). Successful exploitation can lead to full system takeover. Exploitable via __entity. Mitigation: upgrade to 4.9.0 or later.
Original description
The description as published by the source.
CedarJava is an open source Java implementation of the Cedar policy language, used for fine-grained authorization decisions. In versions prior to 2.3.6, 3.4.1 and 4.9.0, under certain circumstances, improper input handling could allow Record-to-Entity type confusion across the Java-Rust FFI boundary. CedarJava sends authorization requests to the Rust cedar-policy evaluator as JSON. The JSON protocol reserves magic single-key object shapes (__entity and __extn) for entity references and extension values. When serializing a CedarMap, there is no validation preventing these reserved keys from being used. If an integrating service builds a CedarMap from caller-supplied key/value data (such as request headers, user-defined metadata, or resource tags), an actor who controls those keys could cause the Rust evaluator to interpret a record as an entity reference. This issue requires the integrating service to build a CedarMap where the an actor controls the keys, and a policy must reference that value in a when/unless clause. This vulnerability has been fixed in versions 2.3.6, 3.4.1, and 4.9.
Source: GitHub Security Advisories (Global) 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-2026-55772 has been found in com.cedarpolicy:cedar-java.
Attackers can target a specific entry point like __entity over the network to misuse the product.
Successful exploitation can lead to full system takeover. CVSS score: 8.8/10.
What to do: upgrade com.cedarpolicy:cedar-java to 4.9.0 or later.
If unsure, ask your IT team or search "com.cedarpolicy:cedar-java CVE-2026-55772" on the vendor's site.
CVE-2026-55772 (com.cedarpolicy:cedar-java) — CWE-843 / CVSS v3 8.8
Attack vector: remote (network-reachable) / no user interaction
Attack surface: __entity / __extn / CedarMap
Patched: 4.9.0 — apply immediately
Workaround: Enable schema-based request validation to catch type mismatches.
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.
A vulnerability (CWE-843) exists in com.cedarpolicy:cedar-java. Attackers reach the vulnerable code path via __entity.
Check the vendor advisory for the affected versions of com.cedarpolicy:cedar-java. Attack surface: __entity / __extn / CedarMap.
Severity: High (CVSS 8.8/10). Successful exploitation can lead to full system takeover.
Update to 4.9.0.
Workaround: Enable schema-based request validation to catch type mismatches.
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
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1Identify exposure identify
Audit SBOM/dependencies for affected components.資産台帳・SBOM・依存マニフェストで com.cedarpolicy:cedar-java を使っているサービスとバージョンを洗い出す。
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2Apply temporary workaround mitigate
Enable schema-based request validation to catch type mismatches.パッチが適用されるまでの応急処置として、Enable schema-based request validation to catch type mismatches. を実施。回避策の副作用 (機能低下) を確認した上で。
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3Apply patch patch
Upgrade com.cedarpolicy:cedar-java to 4.9.0ステージング環境で 4.9.0 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。
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4Post-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
References
- advisory github.com
- advisory nvd.nist.gov
- advisory github.com
- package github.com
- web github.com