Threats / GNU / CVE-2023-4911
CVE-2023-4911
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-06-22
GNU C Library vulnerability
GNU C Library's dynamic loader contains a buffer overflow in GLIBC_TUNABLES environment variable processing, enabling local privilege escalation and code execution.
Verdict
Today item — known-exploited.
A local attacker can exploit this buffer overflow to execute arbitrary code with elevated privileges on affected systems. Active exploitation in the wild increases risk. Immediate patching of GNU C Library is critical for systems where untrusted users have local access.
01
Is it exploitable?
— the evidence, ranked above the scoreExploit available
Public proof-of-concept exploit code is cataloged for this vulnerability.We link the existence of the exploit; we do not host or redistribute payloads.
Reported exploitation
9 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2023-11-21).
Probability (EPSS)
EPSS 0.78607 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
Affected: GNU, GNU C Library. Confirm exact fixed builds in the vendor advisory.
Weakness (CWE)
Mapped to CWE-122 Heap-based Buffer Overflow — weakness family: Memory safety.CWE assignment from the public NVD record; the weakness class drives how the flaw is exploited.
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
I craft a malicious GLIBC_TUNABLES environment variable to overflow the buffer in ld.so during process initialization.
Business
Unauthorized code execution on production systems compromises data confidentiality, integrity, and availability.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I escalate my privileges from a standard user account to root or system level through the overflow mechanism.
Business
Full system compromise enables attackers to install persistence mechanisms, access sensitive data, and pivot to other infrastructure.
3
Lateral reach — past segmentation narrative 3
Attacker
I execute arbitrary payloads with elevated privileges to establish backdoors or exfiltrate protected information.
Business
Breach of confidential data and loss of system control creates regulatory exposure and operational disruption.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05
Coverage & confidence
— what we know, and what we don’tEstablished (cited)
Coverage gaps — stated, not hidden
Disclosure & credit2
Catalogued by redhatCNA
Credited with finding itRed Hat would like to thank Qualys Research Labs for reporting this issue.unspecified