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Fencer Vulns
high 7.5

CVE-2020-36228 in the critical feed json

An integer underflow was discovered in OpenLDAP before 2.4.57 leading to a slapd crash in the Certificate List Exact Assertion processing,…

published 2021-01-25 5 y ago modified 2026-10-14 26 d ago also BIT-openldap-2020-36228 , EUVD-2020-23773 , JLSEC-2026-170

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
85.0%
EPSS 85.0% chance of exploitation in 30 days, percentile 99.7%
public exploits
0
none known

Summary

An integer underflow was discovered in OpenLDAP before 2.4.57 leading to a slapd crash in the Certificate List Exact Assertion processing, resulting in denial of service.

Patch / fix

  • bitnami openldap 2.4.57
  • julia OpenLDAPClient_jll 2.5.14+0
  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP V3.1.5
  • Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP V3.1.5
  • Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP V3.1.5
  • openldap Debian 14, Debian 13, Debian 12 2.4.57+dfsg-1

debian advisories DEBIAN-CVE-2020-36228

  • openldap Ubuntu 16.04 LTS 2.4.42+dfsg-2ubuntu3.12
  • openldap Ubuntu 18.04 LTS 2.4.45+dfsg-1ubuntu1.9
  • openldap Ubuntu 20.04 LTS 2.4.49+dfsg-2ubuntu1.6
  • openldap Ubuntu Pro 14.04 LTS 2.4.31-1+nmu2ubuntu8.5+esm7

ubuntu advisories UBUNTU-CVE-2020-36228

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • openldap2 SLES 11 SP4-LTSS, SLE Point of Sale 11 SP3 2.4.26-0.74.26.1
  • openldap2-client SLES 11 SP4-LTSS, SLE Point of Sale 11 SP3 2.4.26-0.74.26.1
  • openldap2-client-openssl1 SLES 11-SECURITY 2.4.26-0.74.26.1
  • openldap2 SLES for SAP 15 SP1, SLES for SAP 15, SLES 15-LTSS +13 more 2.4.46-9.48.1
  • openldap2 SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES for SAP 12 SP3 +14 more 2.4.41-18.83.1
  • openldap2 SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES for SAP 12 SP3 +2 more 2.4.41-39.1

suse advisories SUSE-SU-2021:14700-1SUSE-SU-2021:0723-1SUSE-SU-2021:0693-1SUSE-SU-2021:0692-1

  • openldap2 openSUSE Leap 15.2 2.4.46-lp152.14.18.1

opensuse advisories openSUSE-SU-2021:0408-1

  • openldap Alpine 3.24, Alpine 3.23, Alpine 3.22 +9 more 2.4.57-r0

alpine advisories ALPINE-CVE-2020-36228

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • openldap Arch Linux 2.4.57-1

arch linux advisories AVG-1489

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2020-36228 updated cvss 7.5

openldap: Integer underflow in issuerAndThisUpdateCheck in schema_init.c

  • Red Hat Enterprise Linux 6 openldap, compat-openldap, openldap-clients, openldap-servers, openldap-servers-sql Red Hat Enterprise Linux 7 openldap, compat-openldap, openldap-clients, openldap-servers, openldap-servers-sql
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 8 openldap, openldap-clients, openldap-servers Red Hat Enterprise Linux 9 openldap, openldap-compat, openldap-clients
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

cisa ICSA-23-348-10 updated cvss 7.5

Siemens SIMATIC S7-1500

  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) >= 3.1.0, < 3.1.5 Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) >= 3.1.0, < 3.1.5 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) >= 3.1.0, < 3.1.5 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) >= 3.1.0, < 3.1.5 Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) >= 3.1.0, < 3.1.5
    affected: fixed in V3.1.5, mitigation support.industry.siemens.com

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

Exploit prediction

84.99% chance of exploitation in the next 30 days, higher than 99.7% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P
OSV 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
bitnami openldap
<2.4.57
2.4.57
julia OpenLDAPClient_jll
<2.5.14+0
2.5.14+0

Affected products

  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP
  • Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP
  • Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP

Classification

Weakness
  • CWE-191 Integer Underflow (Wrap or Wraparound)

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.