flatted vulnerable to unbounded recursion DoS in parse() revive phase

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

• CVE-2026-32141: 0.84% estimated exploitation activity in the next 30 days; percentile 57.89 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary flatted's parse() function uses a recursive revive() phase to resolve circular references in deserialized JSON. When given a crafted payload with deeply nested or self-referential $ indices, the recursion depth is unbounded, causing a stack overflow that crashes the Node.js process. Impact Denial of Service (DoS). Any application that passes untrusted input to flatted.parse() can be crashed by an unauthenticated attacker with a single request. flatted has ~87M weekly npm downloads and is used as the circular-JSON serialization layer in many caching and logging libraries. Proof of Concept Fix The maintainer has already merged an iterative (non-recursive) implementation in PR #88, converting the recursive revive() to a stack-based loop. Affected Versions All versions prior to the PR #88 fix.

Published by the source

13 Mar 2026, 15:40 UTC

Last modified by the source

10 Sep 2026, 03:50 UTC

Source last checked

26 Oct 2026, 12:46 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-25h7-pfq9-p65f

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-25h7-pfq9-p65f

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# Patch Next advisory brief: CVE-2026-32141

Advisory: flatted vulnerable to unbounded recursion DoS in parse() revive phase
IDs: CVE-2026-32141, GHSA-25h7-pfq9-p65f
Record: https://patchnext.com/advisories/cve-2026-32141 (revision 2, source checked 26 Oct 2026, 12:46 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: flatted 3.4.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm flatted: affected < 3.4.0; fixed in 3.4.0

## Suggested inspection (read-only)
- `npm ls flatted --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## 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 flatted.
- 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://osv.dev/vulnerability/GHSA-25h7-pfq9-p65f (OSV record GHSA-25h7-pfq9-p65f lists affected ranges: npm flatted >=0 <3.4.0 (fixed))
- Verified: https://github.com/advisories/GHSA-25h7-pfq9-p65f (GitHub-reviewed advisory GHSA-25h7-pfq9-p65f lists affected ranges: npm flatted >=0 <3.4.0)

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