Skip to content
Fencer Vulns
critical 9.8

CVE-2019-18224 json

idn2_to_ascii_4i in lib/lookup.c in GNU libidn2 before 2.1.1 has a heap-based buffer overflow via a long domain string.

published 2019-10-21 7 y ago modified 2026-10-14 26 d ago also EUVD-2019-8024

cvss
9.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
3.7%
EPSS 3.7% chance of exploitation in 30 days, percentile 89%
public exploits
0
none known

Summary

idn2_to_ascii_4i in lib/lookup.c in GNU libidn2 before 2.1.1 has a heap-based buffer overflow via a long domain string.

Patch / fix

  • 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
  • libidn2 Debian 14, Debian 13, Debian 12 2.2.0-1

debian advisories DEBIAN-CVE-2019-18224

  • libidn2 Ubuntu 18.04 LTS 2.0.4-1.1ubuntu0.2

ubuntu advisories UBUNTU-CVE-2019-18224

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

  • libidn2 RHEL 8 2.2.0-1.el8
  • idn2 RHEL 8 2.2.0-1.el8

red hat advisories RHBA-2019:3621

  • libidn2 SLE Module for Basesystem 15 SP1, SLE Module for Basesystem 15 2.2.0-3.3.1

suse advisories SUSE-SU-2019:3086-1

  • libidn2 openSUSE Leap 15.0 2.2.0-lp150.2.3.1
  • libidn2 openSUSE Leap 15.1 2.2.0-lp151.3.3.1

opensuse advisories openSUSE-SU-2019:2613-1openSUSE-SU-2019:2611-1

  • libidn2 AlmaLinux 8 2.2.0-1.el8
  • idn2 AlmaLinux 8 2.2.0-1.el8

almalinux advisories ALBA-2019:3621

  • libidn2 Alpine 3.24, Alpine 3.23, Alpine 3.22 +10 more 2.1.1-r0

alpine advisories ALPINE-CVE-2019-18224

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

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-2019-18224 updated cvss 5.6

libidn2: heap-based buffer overflow in idn2_to_ascii_4i in lib/lookup.c

  • Red Hat CodeReady Linux Builder (v. 8) libidn2-devel 2.2.0-1.el8, idn2-debuginfo 2.2.0-1.el8, libidn2-debuginfo 2.2.0-1.el8, libidn2-debugsource 2.2.0-1.el8 Red Hat Enterprise Linux AppStream (v. 8) idn2 2.2.0-1.el8 Red Hat Enterprise Linux BaseOS (v. 8) libidn2 2.2.0-1.el8
    fixed: vendor fix RHBA-2019:3621

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 9.8

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

3.71% chance of exploitation in the next 30 days, higher than 89% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • bugs.chromium.org https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=12420 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P

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

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.