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CVE-2021-40438: Apache HTTP Server-Side Request Forgery (SSRF)

criticalknown exploitedpublic exploitCVE-2021-40438
Actively exploited. At least one CVE in this advisory is listed in the CISA Known Exploited Vulnerabilities catalog — exploitation has been observed in the wild. Treat remediation as urgent.
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.

CSIRTS triage

vendor: Apacheproduct: HTTP ServerServer-side request forgeryaffected: 2.4.48 and earlier
What
A crafted request can cause mod_proxy to forward requests to an attacker-controlled origin server.
Who is affected
Deployments of Apache HTTP Server version 2.4.48 and earlier.
Urgency
Immediate remediation is necessary due to active exploitation and critical severity.
Action
Upgrade to Apache HTTP Server version 2.4.49 or later.

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Details

Source
CISA Known Exploited Vulnerabilities (US · database · site)
Severity
critical
Published
2021-12-01
Exploitation
Observed in the wild (CISA KEV)

Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2021-40438

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Referenced CVEs

CVECSIRTS overviewExternal
CVE-2021-40438coverage & exploitation statusNVD · CVE.org

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