Description
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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| — | glibc | 2.34 – < 2.39 | 2.39 |
| Red Hat | Red Hat Enterprise Linux 8 | — | — |
| Red Hat | Red Hat Enterprise Linux 8.6 Extended Update Support | — | — |
| Red Hat | Red Hat Enterprise Linux 9 | — | — |
| Red Hat | Red Hat Enterprise Linux 9.0 Extended Update Support | — | — |
| Red Hat | Red Hat Virtualization 4 for Red Hat Enterprise Linux 8 | — | — |
| Red Hat | Red Hat Enterprise Linux 6 | — | — |
| Red Hat | Red Hat Enterprise Linux 7 | — | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | glibc | 2.37-12 | — |
| Debian 13 | glibc | 2.37-12 | — |
| Debian 12 | glibc | 2.36-9+deb12u3 | DSA-5514-1 |
| Debian 11 | glibc | 2.31-13+deb11u7 | DSA-5514-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 24.04 LTS | glibc | 2.38-1ubuntu6 | — |
| Ubuntu 22.04 LTS | glibc | 2.35-0ubuntu3.4 | USN-6409-1 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 9 | nscd +214 | 2.34-60.el9_2.7 | RHSA-2023:5453 |
| RHEL 8 | nscd +213 | 2.28-225.el8_8.6 | RHSA-2023:5455 |
Show 3 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Red Hat Rhev Hypervisor 4 | glibc-devel +1 | 2.28-189.6.el8_6 | RHSA-2023:5476 |
| Red Hat Rhev Hypervisor 4 | redhat-release-virtualization-host +2 | 4.5.3-10.el8ev | RHSA-2024:0033 |
| Red Hat Rhev Hypervisor 4 | redhat-virtualization-host +1 | 4.5.3-202312060823_8.6 | RHSA-2024:0033 |
| RHEL 9.0 EUS | nscd +214 | 2.34-28.el9_0.4 | RHSA-2023:5454 |
| RHEL 8.6 EUS | nscd +213 | 2.28-189.6.el8_6 | RHSA-2023:5476 |
AlmaLinux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux 9 | nscd +214 | 2.34-60.el9_2.7 | ALSA-2023:5453 |
| AlmaLinux 8 | nscd +213 | 2.28-225.el8_8.6 | ALSA-2023:5455 |
Rocky Linux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Rocky Linux 8 | glibc | 2.28-225.el8_8.6 | RLSA-2023:5455 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | glibc | 2.38-4.1 | openSUSE-SU-2024:13294-1 |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2023 | nscd +217 | 2.34-52.amzn2023.0.6 | ALAS2023-2023-359 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | glibc | 2.38-6 | — |
| Azure Linux 2 (CBL-Mariner) | glibc | 2.35-5 | — |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 9 | nscd +214 | 2.34-60.0.3.el9 | ELSA-2023-12850, ELSA-2023-5453 |
| Oracle Linux 8 | nscd +213 | 2.28-225.0.4.el8 | ELSA-2023-12851, ELSA-2023-5455 |
Wolfi
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Wolfi rolling | glibc | 2.38-r5 | — |
Public exploits
Exploit or proof-of-concept code for this vulnerability is publicly available, which lowers the bar for attackers. Treat it as a reason to patch sooner.
Third-party code, not reviewed by us. Public PoCs are sometimes fake or contain malware. Read the code first and run it only in an isolated lab, against systems you are authorised to test.
Metasploit 1 module
-
Glibc Tunables Privilege Escalation CVE-2023-4911 (aka Looney Tunables)
exploit/linux/local/glibc_tunables_priv_esc
Exploit-DB 1
- glibc 2.38 - Buffer Overflow EDB-52479 · local · Feb 11, 2026
GitHub 22 repositories · most starred shown
-
leesh3288/CVE-2023-4911 ★ 393 · Oct 4, 2023
PoC for CVE-2023-4911
-
RickdeJager/CVE-2023-4911 ★ 167 · Oct 4, 2023
CVE-2023-4911 proof of concept
-
chaudharyarjun/LooneyPwner ★ 43 · Oct 17, 2023
Exploit tool for CVE-2023-4911, targeting the 'Looney Tunables' glibc vulnerability in various Linux distributions.
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hadrian3689/looney-tunables-CVE-2023-4911 ★ 29 · Oct 10, 2023
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ruycr4ft/CVE-2023-4911 ★ 19 · Oct 11, 2023
CVE-2023-4911
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KernelKrise/CVE-2023-4911 ★ 17 · Oct 25, 2023
Looney Tunables Local privilege escalation (CVE-2023-4911) workshop
-
Green-Avocado/CVE-2023-4911 ★ 15 · Oct 4, 2023
https://www.qualys.com/2023/10/03/cve-2023-4911/looney-tunables-local-privilege-escalation-glibc-ld-so.txt
-
NishanthAnand21/CVE-2023-4911-PoC ★ 8 · Jan 20, 2024
Repository containing a Proof of Concept (PoC) demonstrating the impact of CVE-2023-4911, a vulnerability in glibc's ld.so dynamic loader, exposing risks related to Looney Tunables.
-
Diego-AltF4/CVE-2023-4911 ★ 8 · Oct 28, 2023
Proof of concept for CVE-2023-4911 (Looney Tunables) discovered by Qualys Threat Research Unit
-
jarpex/cve-2023-4911-exploit-optimized ★ 4 · Jun 29, 2026
Pure C exploit for CVE-2023-4911 (Looney Tunables) — x86_64 & aarch64 implementations. Multi-processing brute-forcing, dynamic calibration, integrated ELF parser.
Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.
Advisories 27
- ALSA-2023:5453 Important: glibc security update AlmaLinux Security Advisories · Oct 29, 2026
- ALSA-2023:5455 Important: glibc security update AlmaLinux Security Advisories · Oct 29, 2026
- SSA-082556 SSA-082556: Vulnerabilities in the additional GNU/Linux subsystem of the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP V3.1.5 Siemens ProductCERT · Oct 13, 2026
- SSA-794697 SSA-794697: Vulnerabilities in the Additional GNU/Linux Subsystem of the SIMATIC S7-1500 TM MFP Before V1.1 Siemens ProductCERT · Oct 13, 2026
- RHSA-2023:5455 Red Hat Security Advisory: glibc security update Red Hat Security Advisories (RHSA) · Jul 15, 2026
- RHSA-2023:5453 Red Hat Security Advisory: glibc security update Red Hat Security Advisories (RHSA) · Jul 15, 2026
- RHSA-2024:0033 Red Hat Security Advisory: Red Hat Virtualization Host 4.4.z SP 1 security update Red Hat Security Advisories (RHSA) · Jul 3, 2026
- RHSA-2023:5476 Red Hat Security Advisory: glibc security update Red Hat Security Advisories (RHSA) · Jul 3, 2026
- RHSA-2023:5454 Red Hat Security Advisory: glibc security update Red Hat Security Advisories (RHSA) · Jul 3, 2026
- ICSA-25-162-05 Siemens SIMATIC S7-1500 CPU family CISA ICS & IT advisories · May 14, 2026
- USN-6409-1 glibc vulnerabilities Ubuntu Security Notices (USN) · Apr 22, 2026
- DSA-5514-1 glibc - security update Debian Security (DSA / DLA) · Mar 9, 2026
- VDE-2026-002 Endress+Hauser: buffer overflow in glibc ld.so leading to privilege escalation CERT@VDE · Mar 2, 2026
- RLSA-2023:5455 Important: glibc security update Rocky Linux Security Advisories · Feb 5, 2026
- openSUSE-SU-2024:13294-1 glibc-2.38-4.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- WID-SEC-2023-2543 GNU libc: Schwachstelle ermöglicht Privilegieneskalation BSI CERT-Bund (WID) · Jun 10, 2025
- NCSC-2025-0187 Kwetsbaarheden verholpen in Siemens producten NCSC-NL (Netherlands) · Jun 10, 2025
- VDE-2024-073 Phoenix Contact: Multiple Vulnerabilities in PLCnext Firmware CERT@VDE · May 22, 2025
- SSA-831302 SSA-831302: Vulnerabilities in the BIOS of the SIMATIC S7-1500 TM MFP before V1.3.0 Siemens ProductCERT · Apr 9, 2024
- ICSA-23-166-11 Siemens SIMATIC S7-1500 TM MFP Linux Kernel CISA ICS & IT advisories · Apr 9, 2024
- ICSA-23-166-10 Siemens SIMATIC S7-1500 TM MFP BIOS CISA ICS & IT advisories · Apr 9, 2024
- WID-SEC-2024-0106 Oracle Communications: Mehrere Schwachstellen BSI CERT-Bund (WID) · Jan 16, 2024
- ELSA-2023-5455 Important: glibc security update (Oracle Linux 8) Oracle Linux Security Advisories (ELSA) · Dec 19, 2023
- ELSA-2023-5453 Important: glibc security update (Oracle Linux 9) Oracle Linux Security Advisories (ELSA) · Oct 10, 2023
- ELSA-2023-12850 Important: glibc security update (Oracle Linux 9) Oracle Linux Security Advisories (ELSA) · Oct 5, 2023
- ELSA-2023-12851 Important: glibc security update (Oracle Linux 8) Oracle Linux Security Advisories (ELSA) · Oct 5, 2023
- ALAS2023-2023-359 Important: glibc security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Oct 3, 2023
References
- RHSA-2023:5453 vendor-advisory
- RHSA-2023:5454 vendor-advisory
- RHSA-2023:5455 vendor-advisory
- RHSA-2023:5476 vendor-advisory
- RHSA-2024:0033 vendor-advisory
- https://access.redhat.com/security/cve/CVE-2023-4911 vdb-entry
- RHBZ#2238352 issue-tracking
- https://www.qualys.com/2023/10/03/cve-2023-4911/looney-tunables-local-privilege-escalation-glibc-ld-so.txt
- https://www.qualys.com/cve-2023-4911/