Vulnerability report

Exploited in the wild Confirmed confidence In CISA KEV

CVE-2023-4911

Glibc: buffer overflow in ld.so leading to privilege escalation

Red Hat Enterprise Linux 8 · affected before *

Watch CVE-2023-4911 Browse KEV feed
Severity
CVSS 7.8 · High
Confidence
Confirmed
Exploit status
Exploited in the wild
EPSS
63.8%
First observed
—
Last observed
—

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2023-4911 is Glibc: buffer overflow in ld.so leading to privilege escalation affecting Red Hat Enterprise Linux 8 and 6 other products. A buffer overflow was discovered in the GNU C Library's dynamic loader ld.so...

Is it exploited?

Yes. Previdian tracks this CVE as a known exploited vulnerability. Confidence is confirmed. Listed in CISA KEV. Also confirmed by third-party sources.

Who is affected?

Red Hat Enterprise Linux 8 affected before *.

What should we do?

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

Overview

Glibc: buffer overflow in ld.so leading to privilege escalation

A buffer overflow was discovered in the GNU C Library's dynamic loader ld.so while processing the GLIBC_TUNABLES environment variable.

This issue could allow a local attacker to use maliciously crafted GLIBC_TUNABLES environment variables when launching binaries with SUID permission to execute code with elevated privileges.

Siemens Affected
SIMATIC S7-1500 CPU 1518-4 PN/DP MFP
Before *
Siemens Affected
SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP
Before *
Siemens Affected
SIPLUS S7-1500 CPU 1518-4 PN/DP MFP
Before *
— Affected
— glibc
Before 2.39
Red Hat Unaffected
Red Hat Enterprise Linux 8 glibc
Before *
Red Hat Unaffected
Red Hat Enterprise Linux 8.6 Extended Update Support glibc
Before *
Red Hat Unaffected
Red Hat Enterprise Linux 9 glibc
Before *
Red Hat Unaffected
Red Hat Enterprise Linux 9.0 Extended Update Support glibc
Before *
Red Hat Unaffected
Red Hat Virtualization 4 for Red Hat Enterprise Linux 8 glibc
Before *
Red Hat Unaffected
Red Hat Virtualization 4 for Red Hat Enterprise Linux 8 redhat-release-virtualization-host
Before *
Red Hat Unaffected
Red Hat Virtualization 4 for Red Hat Enterprise Linux 8 redhat-virtualization-host
Before *
Red Hat Unaffected
Red Hat Enterprise Linux 6 glibc
All versions (default: unaffected)
Red Hat Unaffected
Red Hat Enterprise Linux 7 compat-glibc
All versions (default: unaffected)
Red Hat Unaffected
Red Hat Enterprise Linux 7 glibc
All versions (default: unaffected)
View vendor advisory (opens in new tab)
Published
03 Oct 2023
Exploitation Reported
21 Nov 2023
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None

Tags

linux cisa metasploit

CVE References

  • CVE Record CVE.org · CVE Record https://www.cve.org/CVERecord?id=CVE-2023-4911
  • RHSA-2023:5453 access.redhat.com · Vendor Advisory https://access.redhat.com/errata/RHSA-2023:5453
  • RHSA-2023:5454 access.redhat.com · Vendor Advisory https://access.redhat.com/errata/RHSA-2023:5454
  • RHSA-2023:5455 access.redhat.com · Vendor Advisory https://access.redhat.com/errata/RHSA-2023:5455
  • RHSA-2023:5476 access.redhat.com · Vendor Advisory https://access.redhat.com/errata/RHSA-2023:5476
  • RHSA-2024:0033 access.redhat.com · Vendor Advisory https://access.redhat.com/errata/RHSA-2024:0033
  • RHBZ#2238352 bugzilla.redhat.com · Issue Tracking https://bugzilla.redhat.com/show_bug.cgi?id=2238352
  • VDB Entry — access.redhat.com access.redhat.com · VDB Entry https://access.redhat.com/security/cve/CVE-2023-4911
  • qualys.com/2023/10/03/cve-2023-4911/looney-tunables-loc... qualys.com · CVE Record https://www.qualys.com/2023/10/03/cve-2023-4911/looney-tunables-local...
  • qualys.com/cve-2023-4911 qualys.com · CVE Record https://www.qualys.com/cve-2023-4911/

Exploitation evidence

Why Previdian marks this CVE as exploited

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploited in the wild

CISA

Recorded 21 Nov 2023

A trusted third party reported exploitation.

Proof of concept available

Recorded 28 Apr 2025

Public scanner or PoC coverage increases practical exploitability.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the Previdian Pro API.

Learn about Pro API access
Source Added
CISA First 2023-11-21 00:00 UTC
CVE 2026-06-05 09:28 UTC

Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets
User-Agents
Callback hosts
0
0
0

Request targets and User-Agents available in Pro. Callback host details available in Enterprise.

Virtual patch status

No Previdian virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

Learn about virtual patches →

Scanner Artifacts

Scanner and exploit-framework references linked to this CVE.

Scanner Reference Detected
Metasploit https://github.com/rapid7/metasploit-framework/blob/master/modules/exploits/linux/local/glibc_tunables_priv_esc.rb 28 Apr 2025

Risk and context

Severity, weaknesses, and research context

CVSS v3.1

7.8 High

Potential damage if exploited. Separate from whether attackers are using it.

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS

63.8%

Estimated chance of exploitation in the next 30 days. Previdian's warning comes from evidence, not this score.

Weaknesses

Heap-based Buffer Overflow CWE-122

Potential Proof of Concepts

These PoCs are unverified and could contain malware. Use at your own risk.

glibc_tunables_priv_esc

metasploit · Created Unknown

Metasploit module for CVE-2023-4911

Timeline

From disclosure to observed exploitation

  1. 09:28 UTC

    KEV confirmed by CVE

    Exploitation attested by an external source

  2. 15:02 UTC

    Metasploit module available

    Exploit module available

  3. 15:02 UTC

    Public PoC available

    Public proof-of-concept code published

  4. 00:00 UTC

    Added to CISA KEV

    Listed in the CISA Known Exploited Vulnerabilities catalog

  5. 17:25 UTC

    CVE published

    Vulnerability disclosed publicly

  6. 13:10 UTC

    CVE ID reserved

    Identifier reserved by the CNA

Pro API

Automate this intelligence

Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

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  • Evidence confidence and provenance
  • First-party sensor telemetry
  • PoC and scanner references
  • Affected versions and enrichment
  • Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2023-4911

Free JSON includes basic KEV fields 
{
  "cve_id": "CVE-2023-4911",
  "confidence": "Confirmed",
  "cvss_score": 7.8,
  "cvss_estimated": false,
  "epss_score": 0.63769,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": false
  },
  "sensor_telemetry": { "attempts": 0, "sensors": 0 }
}