Cedar: JSON template is in scope missing slot-id validation allows link panic and decision divergence

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

2.1 · CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:N/VI:N/VA:L/SC:L/SI:L/SA:L · score source

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

Cedar users must be using all of the following features to be affected by this advisory: JSON format policies, policy templates, and the `is in` scope condition. This advisory only affects JSON-formatted Cedar policy templates containing `is in` scope conditions that are malformed according to the Cedar syntax. It does not affect syntactically well-formed policies. Users of Cedar who author policies in the JSON format were able to write Cedar policies using the `is in` condition with an incorrect slot identifier in the principal and resource scope constraints (e.g., `?principal` in the resource scope constraint) even though this is not allowed when parsing policies from the Cedar policy syntax. Internally, the slot identifiers were silently corrected (e.g. `?resource` is placed in the resource scope constraint). If the policy contains *exactly one slot* in either the principal or resource position, then any attempt to create a linked policy from the template results in an…

Published by the source

29 Oct 2026, 16:35 UTC

Last modified by the source

29 Oct 2026, 16:45 UTC

Source last checked

30 Oct 2026, 06:00 UTC

1. Revision 2 · amended · 30 Oct 2026

   Amended from osv record GHSA-c33x-vcv4-vg3g

2. Revision 1 · created · 29 Oct 2026

   Published from ghsa record GHSA-c33x-vcv4-vg3g

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# Patch Next advisory brief: GHSA-c33x-vcv4-vg3g

Advisory: Cedar: JSON template is in scope missing slot-id validation allows link panic and decision divergence
IDs: GHSA-c33x-vcv4-vg3g
Record: https://patchnext.com/advisories/ghsa-c33x-vcv4-vg3g (revision 2, source checked 30 Oct 2026, 06:00 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Low (CVSS 2.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: @cedar-policy/cedar-wasm 4.11.1, 3.4.3; cedar-policy 4.11.1, 3.4.3. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @cedar-policy/cedar-wasm: affected >= 4.0.1, < 4.11.1; >= 3.2.0, < 3.4.3; fixed in 4.11.1, 3.4.3
- crates.io cedar-policy: affected >= 4.0.0, < 4.11.1; >= 3.0.0, < 3.4.3; fixed in 4.11.1, 3.4.3

## Suggested inspection (read-only)
- `npm ls @cedar-policy/cedar-wasm --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.
- crates.io cedar-policy: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on @cedar-policy/cedar-wasm, cedar-policy.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-c33x-vcv4-vg3g (GitHub-reviewed advisory GHSA-c33x-vcv4-vg3g lists affected ranges: crates.io cedar-policy >=4.0.0 =3.0.0 =4.0.1 =3.2.0 <3.4.3)
- Verified: https://osv.dev/vulnerability/GHSA-c33x-vcv4-vg3g (OSV record GHSA-c33x-vcv4-vg3g lists affected ranges: crates.io cedar-policy >=4.0.0 =3.0.0 =4.0.1 =3.2.0 <3.4.3 (fixed))

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