CVE-2021-39176

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

7.5 HighFix available

detect-character-encoding is a package for detecting character encoding using ICU. In detect-character-encoding v0.3.0 and earlier, allocated memory is not released. The problem has been patched in detect-character-encoding v0.3.1.

Attack profile

How easy it is to exploit

Attack vector: Network
Complexity: Low
Privileges needed: None
User interaction: None

What an attacker can affect

Confidentiality: None
Integrity: None
Availability: High

Exploit likelihood

1.89%Up 0.9 points since Sep 1, 2021

What each source reports

CVE List Score used 7.5

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

Record: CVE-2021-39176
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness: CWE-401
Updated: 2026-11-02

EUVDEUVD-2021-1986 7.5

Record: EUVD-2021-1986
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated: 2026-11-03

GitHub AdvisoriesGHSA-5rwj-j5m3-3chj 7.5

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

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

const express = require("express");
const detectCharacterEncoding = require("detect-character-encoding");

const app = express();

app.get("/", (req, res) => {
  detectCharacterEncoding(Buffer.from("foo"));

  res.end();
});

app.listen(3000);

hey -n 1000000 http://localhost:3000 (hey) causes the Node.js process to consume more and more memory.

References

Record: GHSA-5rwj-j5m3-3chj
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness: CWE-401
Updated: 2026-11-02

NVD 7.5

Record: CVE-2021-39176
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 2.0: 5.0 MediumAV:N/AC:L/Au:N/C:N/I:N/A:P
Weakness: CWE-401
Updated: 2026-11-02

OSV 7.5

Record: CVE-2021-39176
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated: 2026-11-02

OSVGHSA-5rwj-j5m3-3chj 7.5

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

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)

Proof of concept

const express = require("express");
const detectCharacterEncoding = require("detect-character-encoding");

const app = express();

app.get("/", (req, res) => {
  detectCharacterEncoding(Buffer.from("foo"));

  res.end();
});

app.listen(3000);

hey -n 1000000 http://localhost:3000 (hey) causes the Node.js process to consume more and more memory.

References

Record: GHSA-5rwj-j5m3-3chj
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness: CWE-401
Updated: 2026-11-02

Affected products

Affected packages

Affected packages
Package	Affected	Fixed
`detect-character-encoding` npm	before 0.3.1	0.3.1

History

History
Recorded	Changed	Sources
Nov 3, 2026	aliases	EUVD
Nov 2, 2026	first indexed	CVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2021-39176 is a high vulnerability (CVSS 7.5) in Detect-character-encoding Project Detect-character-encoding, published August 31, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.89%, the 79th percentile. Fixed in detect-character-encoding 0.3.1.