---
id: CVE-2021-27645
title: >-
  The nameserver caching daemon (nscd) in the GNU C Library (aka glibc or libc6)
  2.29 through 2.33, when processing a request for netgroup lookup, may crash
  due to a double-free, potentially resulting in degraded service or Denial of
  Servi…
summary: >-
  The nameserver caching daemon (nscd) in the GNU C Library (aka glibc or libc6)
  2.29 through 2.33, when processing a request for netgroup lookup, may crash
  due to a double-free, potentially resulting in degraded service or Denial of
  Servi…
severity: low
cvss: 2.5
cvssVector: 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L'
cwe:
  - CWE-415
  - CWE-415
vendor: gnu
product: glibc
affected:
  - 'glibc >= 2.29, <= 2.33'
  - fedora = 33
  - fedora = 34
  - debian_linux = 10.0
published: '2021-02-24'
updated: '2026-10-14'
sourceUpdated: '2026-10-14T12:17:10.460'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2021-27645'
references:
  - url: 'https://lists.debian.org/debian-lts-announce/2022/10/msg00021.html'
    label: cve@mitre.org
  - url: >-
      https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/7LZNT6KTMCCWPWXEOGSHD3YLYZKUGMH5/
    label: cve@mitre.org
  - url: >-
      https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/I7TS26LIZSOBLGJEZMJX4PXT5BQDE2WS/
    label: cve@mitre.org
  - url: 'https://security.gentoo.org/glsa/202107-07'
    label: cve@mitre.org
  - url: 'https://sourceware.org/bugzilla/show_bug.cgi?id=27462'
    label: cve@mitre.org
  - url: 'https://lists.debian.org/debian-lts-announce/2022/10/msg00021.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/7LZNT6KTMCCWPWXEOGSHD3YLYZKUGMH5/
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/I7TS26LIZSOBLGJEZMJX4PXT5BQDE2WS/
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://security.gentoo.org/glsa/202107-07'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://sourceware.org/bugzilla/show_bug.cgi?id=27462'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-398330.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-831302.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
epss: 0.00374
epssPercentile: 0.29534
ingestedAt: '2026-10-14T12:29:10.816Z'
---

## Overview

The nameserver caching daemon (nscd) in the GNU C Library (aka glibc or libc6) 2.29 through 2.33, when processing a request for netgroup lookup, may crash due to a double-free, potentially resulting in degraded service or Denial of Service on the local system. This is related to netgroupcache.c.

## Affected

- `glibc >= 2.29, <= 2.33`
- `fedora = 33`
- `fedora = 34`
- `debian_linux = 10.0`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.