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Exploited vulnerability · CISA KEV

Is CVE-2021-40438 exploited? Yes: in CISA KEV since 1 Dec 2021

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

Yes. CVE-2021-40438, Apache HTTP Server-Side Request Forgery (SSRF), is being exploited in the wild. CISA added it to its Known Exploited Vulnerabilities catalog on 1 Dec 2021, 76 days after it was published. It is known to be used in ransomware campaigns. It affects Apache. If you run it, CISA's required action is: Apply updates per vendor instructions.

exploitedYesCISA KEV · 1 Dec 2021
ransomwareKnownused in campaigns
EPSStop 1%among the most likely CVEs to be exploited
severity9CVSS 3.1 · critical
US federal due15 Dec 2021BOD 22-01 deadline

What it is

A crafted request uri-path can cause mod_proxy to forward the request to an origin server choosen by the remote user. This issue affects Apache HTTP Server 2.4.48 and earlier.

VendorApache (41 exploited CVEs in KEV)
ProductApache
VulnerabilityApache HTTP Server-Side Request Forgery (SSRF)
WeaknessCWE-918
Published16 Sep 2021
Added to KEV1 Dec 2021
Reported by (CNA)apache

What to do

  1. Check whether you run it. Look for Apache 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 16 Sep 2021.
  4. Get told next time. Email alerts when CISA adds a CVE for Apache.

References

Questions

Is CVE-2021-40438 being exploited?

Yes. CISA added CVE-2021-40438 to the Known Exploited Vulnerabilities catalog on 1 Dec 2021, which means there is reliable evidence of exploitation in the wild.

Is CVE-2021-40438 used in ransomware attacks?

Yes, CISA lists it as known to be used in ransomware campaigns.

How do I fix CVE-2021-40438?

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 Apache 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 December 2021 · Apache scorecard · act-now radar.

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