CVEs / CVE-2021-40438
CVE-2021-40438: Apache HTTP Server-Side Request Forgery (SSRF)
- Known exploited in the CISA KEV catalog since 1 Dec 2021
- critical 9 CVSS 3.1 (NVD)
- EPSS 99.9% chance of exploitation in the next 30 days, higher than 99% of CVEs (30 Oct 2026)
- Last changed at its sources
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Summary
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.
Description
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.
Affected and fixed versions
| Product | Affected | Fixed in |
|---|---|---|
| Apache Software Foundation Apache HTTP Server | from Apache HTTP Server 2.4, up to and including 2.4.48 | — |
Exploitation
| In CISA KEV since | 1 Dec 2021 |
|---|---|
| Due date for US federal agencies | 15 Dec 2021 |
| Used in ransomware campaigns | Known |
| Required action | Apply updates per vendor instructions. |
Severity
| CVSS 3.1 | 9 criticalCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:HScored by NVD |
|---|---|
| Weakness | CWE-918 |
References
- CVE-2021-40438 on NVD
- CVE-2021-40438 in the CISA KEV catalog
- CVE-2021-40438 on OSV
- https://cert-portal.siemens.com/productcert/pdf/ssa-685781.pdf Third Party Advisory
- https://httpd.apache.org/security/vulnerabilities_24.html Release Notes, Vendor Advisory
- https://lists.apache.org/thread.html/r210807d0bb55f4aa6fbe1512be6bcc4dacd64e84940429fba329967a%40%3Cusers.httpd.apache.org%3E Mailing List
- https://lists.apache.org/thread.html/r2eb200ac1340f69aa22af61ab34780c531d110437910cb9c0ece3b37%40%3Cbugs.httpd.apache.org%3E Mailing List
- https://lists.apache.org/thread.html/r3925e167d5eb1c75def3750c155d753064e1d34a143028bb32910432%40%3Cusers.httpd.apache.org%3E Mailing List
- https://lists.apache.org/thread.html/r61fdbfc26ab170f4e6492ef3bd5197c20b862ce156e9d5a54d4b899c%40%3Cusers.httpd.apache.org%3E Mailing List
- https://lists.apache.org/thread.html/r82838efc5fa6fc4c73986399c9b71573589f78b31846aff5bd9b1697%40%3Cusers.httpd.apache.org%3E Mailing List
- https://lists.apache.org/thread.html/r82c077663f9759c7df5a6656f925b3ee4f55fcd33c889ba7cd687029%40%3Cusers.httpd.apache.org%3E Mailing List
- https://lists.apache.org/thread.html/rf6954e60b1c8e480678ce3d02f61b8a788997785652e9557a3265c00%40%3Cusers.httpd.apache.org%3E Mailing List
- https://lists.debian.org/debian-lts-announce/2021/10/msg00001.html Mailing List, Third Party Advisory
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/SPBR6WUYBJNACHKE65SPL7TJOHX7RHWD/ Release Notes
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZNCYSR3BXT36FFF4XTCPL3HDQK4VP45R/ Release Notes
- https://security.gentoo.org/glsa/202208-20 Third Party Advisory
- https://security.netapp.com/advisory/ntap-20211008-0004/ Third Party Advisory
- https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-apache-httpd-2.4.49-VWL69sWQ Broken Link, Third Party Advisory
- https://www.debian.org/security/2021/dsa-4982 Mailing List, Third Party Advisory
- https://www.oracle.com/security-alerts/cpuapr2022.html Patch, Third Party Advisory
- https://www.oracle.com/security-alerts/cpujan2022.html Patch, Third Party Advisory
- https://www.tenable.com/security/tns-2021-17 Third Party Advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-40438 US Government Resource
Sources
Exploitation status from the CISA Known Exploited Vulnerabilities catalog. EPSS scores from FIRST. Descriptions, severity and references from the National Vulnerability Database. Open-source package versions from OSV (CC-BY 4.0). Text is shown as each source states it; Stackurity does not edit it. Check the vendor's advisory before acting.
This product uses data from the NVD API but is not endorsed or certified by the NVD.