CVE-2023-4911

GNU C Library: Buffer Overflow

As of , CVE-2023-4911 in GNU C Library is on CISA's list of exploited vulnerabilities: CISA listed it on . Our patch-first group: Patch this week.

Exploited
Yes: CISA listed it on 21 November 2023
US federal deadline
12 December 202321 days after CISA listed it. US federal civilian agencies must fix it by then.
Used in ransomware campaigns
Not known to CISA
EPSS score
0.64Higher than 99% of the CVEs EPSS scores. EPSS estimates the chance of exploitation activity in the next 30 days.
EPSS when listed
0.00 on 21 November 2023EPSS on the day CISA listed it.
Public exploit
1 Metasploit module and 1 Exploit-DB entry
Fix
Vendor advice: access.redhat.com and sourceware.orgLinks below, from CISA's entry.

What CISA says to do

Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

CISA's required action

  • sourceware.orgThis vulnerability affects a common open-source component, third-party library, or a protocol used by different products. Please check…
  • access.redhat.comh=1056e5b4c3f2d90ed2b4a55f96add28da2f4c8fa,

What the flaw is

GNU C Library's dynamic loader ld.so contains a buffer overflow vulnerability when processing the GLIBC_TUNABLES environment variable, allowing a local attacker to execute code with elevated privileges.

CISA's 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.

The CVE record's description, from redhat

CVE published
3 October 2023
Assigned by
redhat
CVSS
7.8 High (CVSS 3.1, from the CNA)
CWE-122
Heap-based Buffer Overflow
CISA SSVC, exploitation
active
CISA SSVC, automatable
no
CISA SSVC, technical impact
total

Timeline

  1. The CVE record was published.
  2. CISA added it to its list of exploited vulnerabilities.
  3. The US federal deadline to fix it.
  4. Exploit-DB published an exploit (EDB-ID 52479).

Public exploits

Facts from Metasploit's module list and Exploit-DB's index; we never copy exploit code.

  • Metasploit: Glibc Tunables Privilege Escalation CVE-2023-4911 (aka Looney Tunables)exploit module, rank excellent
  • Exploit-DB: glibc 2.38 - Buffer OverflowEDB-ID 52479, 11 February 2026

Read further