CVE catalog

CVE-2021-46823

python-ldap: CVE-2021-46823

Severity: Medium · CVSS 6.5CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Published: Jan 1, 2021, 12:00:00 AM UTC
Source: [NVD] · [CVE record]
EPSS: 1.94% · Oct 25, 2026

python-ldap before 3.4.0 is vulnerable to a denial of service when ldap.schema is used for untrusted schema definitions, because of a regular expression denial of service (ReDoS) flaw in the LDAP schema parser. By sending crafted regex input, a remote authenticated attacker could exploit this vulnerability to cause a denial of service condition.

Vulnerable and fixed packages

Distribution-reported package versions and fixes. These do not depend on matching against the OpenFactory package catalog.

Distribution	Package	Release	Version	Status
Debian	python-ldap	sid	`3.4.8-1`	fixed
Debian	python-ldap	forky	`3.4.8-1`	fixed
Debian	python-ldap	trixie	`3.4.4-1+deb13u1`	fixed
Debian	python-ldap	bookworm	`3.4.3-2+deb12u1`	fixed
Ubuntu	python-ldap	18.04	`2.4.41-1`	vulnerable
Ubuntu	python-ldap	18.04	`2.5.2-1`	vulnerable
Ubuntu	python-ldap	18.04	`3.0.0~b4-1`	vulnerable
Ubuntu	python-ldap	18.04	`3.0.0-1`	vulnerable
Ubuntu	python-ldap	18.04	`3.0.0-1ubuntu0.1`	vulnerable
Ubuntu	python-ldap	18.04	`3.0.0-1ubuntu0.2`	fixed
Ubuntu	python-ldap	20.04	`3.1.0-2build1`	vulnerable
Ubuntu	python-ldap	20.04	`3.1.0-2build2`	vulnerable
Ubuntu	python-ldap	20.04	`3.2.0-3`	vulnerable
Ubuntu	python-ldap	20.04	`3.2.0-3ubuntu1`	vulnerable
Ubuntu	python-ldap	20.04	`3.2.0-3ubuntu2`	vulnerable
Ubuntu	python-ldap	20.04	`3.2.0-3ubuntu3`	vulnerable
Ubuntu	python-ldap	20.04	`3.2.0-4ubuntu2`	vulnerable
Ubuntu	python-ldap	20.04	`3.2.0-4ubuntu2.1`	fixed
Ubuntu	python-ldap	22.04	`3.2.0-4ubuntu5`	vulnerable
Ubuntu	python-ldap	22.04	`3.2.0-4ubuntu6`	vulnerable
Ubuntu	python-ldap	22.04	`3.2.0-4ubuntu7`	vulnerable
Ubuntu	python-ldap	22.04	`3.2.0-4ubuntu7.1`	fixed
Ubuntu	python-ldap	18.04	`2.4.41-1`	vulnerable
Ubuntu	python-ldap	18.04	`2.5.2-1`	vulnerable
Ubuntu	python-ldap	18.04	`3.0.0~b4-1`	vulnerable
Ubuntu	python-ldap	18.04	`3.0.0-1`	vulnerable
Ubuntu	python-ldap	18.04	`3.0.0-1ubuntu0.1`	vulnerable
Ubuntu	python-ldap	18.04	`3.0.0-1ubuntu0.2`	fixed
Ubuntu	python-ldap	20.04	`3.1.0-2build1`	vulnerable
Ubuntu	python-ldap	20.04	`3.1.0-2build2`	vulnerable
Ubuntu	python-ldap	20.04	`3.2.0-3`	vulnerable
Ubuntu	python-ldap	20.04	`3.2.0-3ubuntu1`	vulnerable
Ubuntu	python-ldap	20.04	`3.2.0-3ubuntu2`	vulnerable
Ubuntu	python-ldap	20.04	`3.2.0-3ubuntu3`	vulnerable
Ubuntu	python-ldap	20.04	`3.2.0-4ubuntu2`	vulnerable
Ubuntu	python-ldap	20.04	`3.2.0-4ubuntu2.1`	fixed
Ubuntu	python-ldap	22.04	`3.2.0-4ubuntu5`	vulnerable
Ubuntu	python-ldap	22.04	`3.2.0-4ubuntu6`	vulnerable
Ubuntu	python-ldap	22.04	`3.2.0-4ubuntu7`	vulnerable
Ubuntu	python-ldap	22.04	`3.2.0-4ubuntu7.1`	fixed

Fixed-version evidence

Distribution	Package	Type	Release	Fixed version	Urgency	Origin	Bugs
Debian	python-ldap	source	sid	`3.4.0-1`	not yet assigned	Not reported	Not reported
Debian	python-ldap	source	forky	`3.4.0-1`	not yet assigned	Not reported	Not reported
Debian	python-ldap	source	trixie	`3.4.0-1`	not yet assigned	Not reported	Not reported
Debian	python-ldap	source	bookworm	`3.4.0-1`	not yet assigned	Not reported	Not reported
Ubuntu	python-ldap	deb	18.04	`3.0.0-1ubuntu0.2`	Not reported	USN-5508-1	Not reported
Ubuntu	python-ldap	deb	20.04	`3.2.0-4ubuntu2.1`	Not reported	USN-5508-1	Not reported
Ubuntu	python-ldap	deb	22.04	`3.2.0-4ubuntu7.1`	Not reported	USN-5508-1	Not reported
Ubuntu	python-ldap	deb	18.04	`3.0.0-1ubuntu0.2`	Not reported	UBUNTU-CVE-2021-46823	Not reported
Ubuntu	python-ldap	deb	20.04	`3.2.0-4ubuntu2.1`	Not reported	UBUNTU-CVE-2021-46823	Not reported
Ubuntu	python-ldap	deb	22.04	`3.2.0-4ubuntu7.1`	Not reported	UBUNTU-CVE-2021-46823	Not reported

OpenFactory catalog packages

[Debian 12 (Bookworm)]

[python3-ldap]Fixed
Source package: [python-ldap]
Details (2)
- 3.4.3-2+deb12u1 · amd64 · bookworm
  Fixed · Fixed: 3.4.0-1
  dsa · python-ldap · debian · bookworm; dsa · python-ldap · debian · 12
- 3.4.3-2+deb12u1 · arm64 · bookworm
  Fixed · Fixed: 3.4.0-1
  dsa · python-ldap · debian · bookworm; dsa · python-ldap · debian · 12
[python3-pyldap]Fixed
Source package: [python-ldap]
Details (2)
- 3.4.3-2+deb12u1 · amd64 · bookworm
  Fixed · Fixed: 3.4.0-1
  dsa · python-ldap · debian · bookworm; dsa · python-ldap · debian · 12
- 3.4.3-2+deb12u1 · arm64 · bookworm
  Fixed · Fixed: 3.4.0-1
  dsa · python-ldap · debian · bookworm; dsa · python-ldap · debian · 12
[python-ldap-doc]Fixed
Source package: [python-ldap]
Details (2)
- 3.4.3-2+deb12u1 · all · bookworm
  Fixed · Fixed: 3.4.0-1
  dsa · python-ldap · debian · bookworm; dsa · python-ldap · debian · 12
- 3.4.3-2+deb12u1 · all · bookworm
  Fixed · Fixed: 3.4.0-1
  dsa · python-ldap · debian · bookworm; dsa · python-ldap · debian · 12

[Debian 13 (Trixie)]

[python3-ldap]Fixed
Source package: [python-ldap]
Details (2)
- 3.4.4-1+deb13u1 · amd64 · trixie
  Fixed · Fixed: 3.4.0-1
  dsa · python-ldap · debian · 13
- 3.4.4-1+deb13u1 · arm64 · trixie
  Fixed · Fixed: 3.4.0-1
  dsa · python-ldap · debian · 13
[python3-pyldap]Fixed
Source package: [python-ldap]
Details (2)
- 3.4.4-1+deb13u1 · amd64 · trixie
  Fixed · Fixed: 3.4.0-1
  dsa · python-ldap · debian · 13
- 3.4.4-1+deb13u1 · arm64 · trixie
  Fixed · Fixed: 3.4.0-1
  dsa · python-ldap · debian · 13
[python-ldap-doc]Fixed
Source package: [python-ldap]
Details (2)
- 3.4.4-1+deb13u1 · all · trixie
  Fixed · Fixed: 3.4.0-1
  dsa · python-ldap · debian · 13
- 3.4.4-1+deb13u1 · all · trixie
  Fixed · Fixed: 3.4.0-1
  dsa · python-ldap · debian · 13

Observed: Oct 23, 2026, 6:04:11 PM UTC

References

[CERT-Bund public advisories] · [Debian Security Tracker] · [FIRST EPSS] · [OSV Package Vulnerability Database] · [Red Hat security advisories and VEX]