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Fencer Vulns
high 8.4

CVE-2023-6246 json

Glibc: heap-based buffer overflow in __vsyslog_internal()

published 2024-01-31 2 y ago modified 2026-10-14 25 d ago also EUVD-2023-58491

cvss
8.4
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
4.8%
EPSS 4.8% chance of exploitation in 30 days, percentile 91%
public exploits
0
none known

Summary

A heap-based buffer overflow was found in the __vsyslog_internal function of the glibc library. This function is called by the syslog and vsyslog functions. This issue occurs when the openlog function was not called, or called with the ident argument set to NULL, and the program name (the basename of argv[0]) is bigger than 1024 bytes, resulting in an application crash or local privilege escalation. This issue affects glibc 2.36 and newer.

Patch / fix

  • gnu glibc 2.39
  • glibc Debian 12 2.36-9+deb12u4
  • glibc Debian 14, Debian 13 2.37-15

debian advisories DEBIAN-CVE-2023-6246

  • glibc Ubuntu 24.04 LTS 2.39-0ubuntu1

ubuntu advisories UBUNTU-CVE-2023-6246

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

  • glibc openSUSE Tumbleweed 2.39-1.2

opensuse advisories openSUSE-SU-2024:13647-1

  • glibc Azure Linux 3.0 2.38-6

azure linux advisories AZL-34735

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

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-2023-6246 updated cvss 8.4

glibc: heap-based buffer overflow in __vsyslog_internal()

  • 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-25-162-05 updated cvss 7.8

Siemens SIMATIC S7-1500 CPU family

  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) >= 3.1.5 Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) >= 3.1.5 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) >= 3.1.5 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) >= 3.1.5 Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) >= 3.1.5
    affected: mitigation, no fix available

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
Proof of concept is public
Automatable
no
Technical impact
total
Assessed
2 y ago

Exploit prediction

4.79% chance of exploitation in the next 30 days, higher than 91% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • packetstormsecurity.com http://packetstormsecurity.com/files/176931/glibc-qsort-Out-Of-Bounds-Read-Write.html referenced PoC, tagged "exploit" by a source, unverified
  • packetstormsecurity.com http://packetstormsecurity.com/files/176932/glibc-syslog-Heap-Based-Buffer-Overflow.html referenced PoC, tagged "exploit" by a source, unverified
  • seclists.org http://seclists.org/fulldisclosure/2024/Feb/3 referenced PoC, tagged "exploit" by a source, unverified
  • seclists.org http://seclists.org/fulldisclosure/2024/Feb/5 referenced PoC, tagged "exploit" by a source, unverified
  • openwall.com https://www.openwall.com/lists/oss-security/2024/01/30/6 referenced PoC, tagged "exploit" by a source, unverified
  • qualys.com https://www.qualys.com/2024/01/30/cve-2023-6246/syslog.txt referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 8.4 CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

  • n/a glibc
  • Red Hat Red Hat Enterprise Linux 6
  • Red Hat Red Hat Enterprise Linux 7
  • Red Hat Red Hat Enterprise Linux 8
  • Red Hat Red Hat Enterprise Linux 9
  • Fedora Fedora
  • 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.