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Fencer Vulns
high 7.5

CVE-2021-3998 json

A flaw was found in glibc.

published 2022-08-24 4 y ago modified 2026-10-14 26 d ago also EUVD-2021-27188

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
2.2%
EPSS 2.2% chance of exploitation in 30 days, percentile 82%
public exploits
0
none known

Summary

A flaw was found in glibc. The realpath() function can mistakenly return an unexpected value, potentially leading to information leakage and disclosure of sensitive data.

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
  • glibc Debian 14, Debian 13, Debian 12 2.33-4

debian advisories DEBIAN-CVE-2021-3998

  • glibc openSUSE Tumbleweed 2.35-1.1

opensuse advisories openSUSE-SU-2024:11850-1

  • glibc CBL-Mariner 2.0 2.35-7

azure linux advisories AZL-10675

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

  • glibc Arch Linux 2.34-1

arch linux advisories AVG-1621

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-2021-3998 updated cvss 7.5

glibc: Unexpected return value from realpath() could leak data based on the application

  • Red Hat Enterprise Linux 6 nscd, glibc, glibc-utils, compat-glibc, glibc-common Red Hat Enterprise Linux 7 nscd, glibc, glibc-utils, compat-glibc, glibc-common Red Hat Enterprise Linux 8 nscd, glibc, libnsl, nss_db, nss_hesiod, glibc-utils, +7 more Red Hat Enterprise Linux 9 nscd, glibc, libnsl, nss_db, nss_hesiod, glibc-utils, +6 more
    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

cisa ICSA-23-166-10 updated cvss 7.5

Siemens SIMATIC S7-1500 TM MFP BIOS

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

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
17 mo ago

Exploit prediction

2.20% chance of exploitation in the next 30 days, higher than 82% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Affected products

  • n/a glibc
  • 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.