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High, CVSS 7.5amended

Missing Release of Memory after Effective Lifetime in detect-character-encoding

CVE-2021-39176GHSA-5rwj-j5m3-3chj

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (detect-character-encoding 0.3.1), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
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-2021-39176: 1.89% estimated exploitation activity in the next 30 days; percentile 79.60 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Impact In detect-character-encoding v0.3.0 and earlier, allocated memory is not released. Patches The problem has been patched in detect-character-encoding v0.3.1. CVSS score CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/RL:O/RC:C Base Score: 7.5 (High) Temporal Score: 7.2 (High) Since detect-character-encoding is a library, the scoring is based on the “reasonable worst-case implementation scenario”, namely, using detect-character-encoding in a program accessible over the internet which becomes unavailable when running out of memory. Depending on your specific implementation, the vulnerability’s severity in your program may be different. Proof of concept hey -n 1000000 http://localhost:3000 (hey) causes the Node.js process to consume more and more memory. References - https://github.com/sonicdoe/detect-character-encoding/commit/d44356927b92e3b13e178071bf6d7c671766f588 - https://github.com/sonicdoe/detect-character-encoding/pull/6

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 2 · amended ·

    Amended from ghsa record GHSA-5rwj-j5m3-3chj

  2. Revision 1 · created ·

    Published from osv record GHSA-5rwj-j5m3-3chj

Agent brief

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# Patch Next advisory brief: CVE-2021-39176

Advisory: Missing Release of Memory after Effective Lifetime in detect-character-encoding
IDs: CVE-2021-39176, GHSA-5rwj-j5m3-3chj
Record: https://patchnext.com/advisories/cve-2021-39176 (revision 2, source checked 26 Oct 2026, 12:21 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: detect-character-encoding 0.3.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm detect-character-encoding: affected < 0.3.1; fixed in 0.3.1

## Suggested inspection (read-only)
- `npm ls detect-character-encoding --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 detect-character-encoding.
- 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-5rwj-j5m3-3chj (OSV record GHSA-5rwj-j5m3-3chj lists affected ranges: npm detect-character-encoding >=0 <0.3.1 (fixed))
- Verified: https://github.com/advisories/GHSA-5rwj-j5m3-3chj (GitHub-reviewed advisory GHSA-5rwj-j5m3-3chj lists affected ranges: npm detect-character-encoding >=0 <0.3.1)

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