Meridian: Multiple defense-in-depth gaps (collection/depth caps, telemetry, retry, fan-out)

Exploitation

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

CVSS

7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

Summary Meridian v2.1.0 (Meridian.Mapping and Meridian.Mediator) shipped with nine defense-in-depth gaps reachable through its public APIs. Two are HIGH severity — the advertised DefaultMaxCollectionItems and DefaultMaxDepth safety caps are silently bypassed on the IMapper.Map(source, destination) overload and anywhere .UseDestinationValue() is configured on a collection-typed property. Four are MEDIUM (constructor invariant bypass, OpenTelemetry stack-trace info disclosure, retry amplification, notification fan-out amplification). Three are LOW (exception message disclosure, dictionary duplicate-key echo, static mediator cache growth under closed-generic types). All nine are patched in v2.1.1. Upgrade is a drop-in NuGet bump; see the v2.1.1 CHANGELOG for the four behavioural changes (constructor selection, OTel default, publisher fan-out cap, retry caps). Severity Matrix |

| Severity | CWE | Finding | Fix | |---|---|---|---|---| | 1 | HIGH | CWE-770 |…

Published by the source

16 Apr 2026, 22:50 UTC

Last modified by the source

16 Apr 2026, 22:50 UTC

Source last checked

26 Oct 2026, 17:04 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-f5v8-v6q3-q4h6

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# Patch Next advisory brief: GHSA-f5v8-v6q3-q4h6

Advisory: Meridian: Multiple defense-in-depth gaps (collection/depth caps, telemetry, retry, fan-out)
IDs: GHSA-f5v8-v6q3-q4h6
Record: https://patchnext.com/advisories/ghsa-f5v8-v6q3-q4h6 (revision 1, source checked 26 Oct 2026, 17:04 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: meridian.mapping 2.1.1; meridian.mediator 2.1.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- NuGet meridian.mapping: affected >= 2.0.0, < 2.1.1; fixed in 2.1.1
- NuGet meridian.mediator: affected >= 2.0.0, < 2.1.1; fixed in 2.1.1

## Suggested inspection (read-only)
- NuGet meridian.mapping: check the installed version with your package manager.
- NuGet meridian.mediator: 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 meridian.mapping, meridian.mediator.
- 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-f5v8-v6q3-q4h6 (GitHub-reviewed advisory GHSA-f5v8-v6q3-q4h6 lists affected ranges: NuGet meridian.mapping >=2.0.0 =2.0.0 <2.1.1)

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