High severity vulnerability that affects PeterO.Cbor

Exploitation

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

CVSS

not scored

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

Impact The CBOR library supports optional tags that enable CBOR objects to contain references to objects within them. Versions earlier than 4.0 resolved those references automatically. While this by itself doesn't cause much of a security problem, a denial of service can happen if those references are deeply nested and used multiple times (so that the same reference to the same object occurs multiple times), and if the decoded CBOR object is sent to a serialization method such as EncodeToBytes, ToString, or ToJSONString, since the objects referred to are expanded in the process and take up orders of magnitude more memory than if the references weren't resolved. The impact of this problem on any particular system varies. In general, the risk is higher if the system allows users to send arbitrary CBOR objects without authentication, or exposes a remote endpoint in which arbitrary CBOR objects can be sent without authentication. Patches This problem is addressed in version 4.0 by…

Published by the source

30 Sep 2019, 19:42 UTC

Last modified by the source

9 Jan 2023, 05:02 UTC

Source last checked

26 Oct 2026, 16:58 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-cxw4-9qv9-vx5h

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# Patch Next advisory brief: GHSA-cxw4-9qv9-vx5h

Advisory: High severity vulnerability that affects PeterO.Cbor
IDs: GHSA-cxw4-9qv9-vx5h
Record: https://patchnext.com/advisories/ghsa-cxw4-9qv9-vx5h (revision 1, source checked 26 Oct 2026, 16:58 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Unrated
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: petero.cbor 4.0.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- NuGet petero.cbor: affected < 4.0.0; fixed in 4.0.0

## Suggested inspection (read-only)
- NuGet petero.cbor: 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 petero.cbor.
- 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-cxw4-9qv9-vx5h (GitHub-reviewed advisory GHSA-cxw4-9qv9-vx5h lists affected ranges: NuGet petero.cbor >=0 <4.0.0)

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