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HIGH · CVSS 7.8 CISA Known Exploited Vulnerability

CVE-2023-4911

GNU C Library Buffer Overflow Vulnerability

GNU C Library

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.

CVSS
7.8
HIGH
EPSS
63.8%
30-day exploitation
Ransomware groups
0
recorded exploiting
Published
3 Oct 2023
CWE-122, CWE-787

Exploitation status

CISA Known Exploited Vulnerabilities

Listed by CISA on 21 November 2023. US federal agencies were required to remediate it by 12 December 2023.

EPSS — exploitation probability

FIRST puts the probability of exploitation activity in the next 30 days at 63.8%, which is higher than 99.2% of all scored vulnerabilities. EPSS is a forecast of activity, not a measure of severity, and it is rescored daily.

CVSS vector

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

Frequently asked questions

Is CVE-2023-4911 being exploited by ransomware groups?

No ransomware group in this database is currently recorded as exploiting CVE-2023-4911.

What does CVE-2023-4911 affect?

CVE-2023-4911 affects GNU C Library. 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.

How severe is CVE-2023-4911?

CVE-2023-4911 is rated HIGH with a CVSS base score of 7.8. EPSS puts the probability of exploitation in the next 30 days at 63.8%, higher than 99.2% of all scored vulnerabilities. It is listed in the CISA Known Exploited Vulnerabilities catalog, with a federal remediation deadline of 12 December 2023.

How should organisations respond to CVE-2023-4911?

Apply the vendor patch for GNU C Library as the first priority, and treat any internet-facing instance as the most urgent. Because this vulnerability is associated with ransomware activity, also review whether the affected systems were reachable before patching, rather than assuming that patching alone closes the incident.