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Exploited vulnerability · CISA KEV

Is CVE-2016-4437 exploited? Yes: in CISA KEV since 3 Nov 2021

Gociux · Apache Shiro · data: CISA KEV, CVE record, FIRST EPSS

Yes. CVE-2016-4437, Apache Shiro Code Execution Vulnerability, is being exploited in the wild. CISA added it to its Known Exploited Vulnerabilities catalog on 3 Nov 2021, 1975 days after it was published. It affects Apache Shiro. If you run it, CISA's required action is: Apply updates per vendor instructions.

exploitedYesCISA KEV · 3 Nov 2021
ransomwareNot knownno confirmed use
EPSStop 1%among the most likely CVEs to be exploited
severity9.8CVSS 3.1 · critical
US federal due3 May 2022BOD 22-01 deadline

What it is

Apache Shiro contains a vulnerability which may allow remote attackers to execute code or bypass intended access restrictions via an unspecified request parameter when a cipher key has not been configured for the "remember me" feature.

VendorApache (41 exploited CVEs in KEV)
ProductShiro
VulnerabilityApache Shiro Code Execution Vulnerability
WeaknessCWE-284
Published7 Jun 2016
Added to KEV3 Nov 2021
Reported by (CNA)redhat

What to do

  1. Check whether you run it. Look for Shiro in your asset inventory, including appliances and cloud images. Stack check lists every exploited Apache CVE at once.
  2. Apply the fix. Apply updates per vendor instructions.
  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 7 Jun 2016.
  4. Get told next time. Email alerts when CISA adds a CVE for Apache.

References

Questions

Is CVE-2016-4437 being exploited?

Yes. CISA added CVE-2016-4437 to the Known Exploited Vulnerabilities catalog on 3 Nov 2021, which means there is reliable evidence of exploitation in the wild.

Is CVE-2016-4437 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-2016-4437?

Apply updates per vendor instructions. Check Apache's advisory for the fixed versions, and if you can't patch quickly, restrict access to the affected Shiro 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 2021 · Apache scorecard · act-now radar.

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