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Exploited vulnerability · CISA KEV

Is CVE-2023-4911 exploited? Yes: in CISA KEV since 21 Nov 2023

Gociux · GNU C Library · data: CISA KEV, CVE record, FIRST EPSS

Yes. CVE-2023-4911, GNU C Library Buffer Overflow Vulnerability, is being exploited in the wild. CISA added it to its Known Exploited Vulnerabilities catalog on 21 Nov 2023, 49 days after it was published. It affects GNU C Library. If you run it, CISA's required action is: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

exploitedYesCISA KEV · 21 Nov 2023
ransomwareNot knownno confirmed use
EPSStop 1%among the most likely CVEs to be exploited
severity7.8CVSS 3.1 · high
US federal due12 Dec 2023BOD 22-01 deadline

What it 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.

VendorGNU (5 exploited CVEs in KEV)
ProductGNU C Library
VulnerabilityGNU C Library Buffer Overflow Vulnerability
WeaknessCWE-122
Published3 Oct 2023
Added to KEV21 Nov 2023
Reported by (CNA)redhat

What to do

  1. Check whether you run it. Look for GNU C Library in your asset inventory, including appliances and cloud images. Stack check lists every exploited GNU CVE at once.
  2. Apply the fix. Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
  3. If you can't patch today, take the affected service off the internet or restrict who can reach it, and check its logs for signs of compromise since 3 Oct 2023.
  4. Get told next time. Email alerts when CISA adds a CVE for GNU.

References

Questions

Is CVE-2023-4911 being exploited?

Yes. CISA added CVE-2023-4911 to the Known Exploited Vulnerabilities catalog on 21 Nov 2023, which means there is reliable evidence of exploitation in the wild.

Is CVE-2023-4911 used in ransomware attacks?

CISA does not list known ransomware use for it. That can change, and exploitation alone is reason to fix it first.

How do I fix CVE-2023-4911?

Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable. Check GNU's advisory for the fixed versions, and if you can't patch quickly, restrict access to the affected GNU C Library and watch it for signs of compromise.

Sources: CISA KEV (exploitation, ransomware use, required action, due date), the CVE record (publication date, CVSS, CNA), NVD and FIRST EPSS (live score). More: all KEV additions in November 2023 · GNU scorecard · act-now radar.

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