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CVE-2021-40438

mod_proxy SSRF

Published: Sep 16, 2021Updated: Oct 27, 2025 Sources: CVE List NVD BDU csafCWE-918
NVD MITRE
9.0CVSSCRITICAL
EPSS Score
100.0%
Top 0.0%
CISA KEV
Active Exploitation
Since Dec 1, 2021
Exploits
No Known Exploits
Remediation
Patch Available
Am I actually vulnerable?1 Nuclei template available — see how to check your systems. How to verify

Description

Multiple vulnerabilities were identified in the Apache HTTP Server software. These include NULL Pointer Dereferencing, Out-of-bounds Write and Server-Side Request Forgery related vulnerabilities. Siemens has released updates for several affected products and recommends to update to the latest versions. Siemens recommends specific countermeasures for products where updates are not, or not yet available.

CVSS Vector Breakdown

AV:NAC:HPR:NUI:NS:CC:HI:HA:H
Exploitability
AV:NAttack Vector
Network
AC:HAttack Complexity
High
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:CScope
Changed
Impact
C:HConfidentiality
High
I:HIntegrity
High
A:HAvailability
High
Open in CVSS calculator →

Weaknesses

CWE-918

Affected Products

rocky linuxresf
Mixed
Operating Systems / linux-distro
enterprise linuxredhat
On-premOS
Operating Systems / linux-distro
enterprise linux eusredhat
OS
Operating Systems / linux-distro
enterprise linux for arm 64redhat
On-premOS
Operating Systems / linux-distro
enterprise linux for arm 64 eusredhat
On-premOS
Operating Systems / linux-distro
resfoss-projectOperating Systemsaka rocky linux
redhatcommercialUSOperating Systemsaka red hat
and 48 more affected products View all →

Attack Graph

Products CVE Techniques Tactics

Click technique nodes to view MITRE ATT&CK details. Scroll to zoom, drag to pan.

Exploitability

CISA Known Exploited Vulnerability
Added to KEV:Dec 1, 2021
Remediation due:Dec 15, 2021

Required action: Apply updates per vendor instructions.

Official Patch Available

MITRE ATT&CK

2 techniques
Command and Control
Initial Access
View detailed technique mapping

References

https://cert-portal.siemens.com/productcert/csaf/ssa-685781.json
cert-portal.siemens.com
https://cert-portal.siemens.com/productcert/txt/ssa-685781.txt
cert-portal.siemens.com
https://cert-portal.siemens.com/productcert/pdf/ssa-685781.pdf
cert-portal.siemens.com
and 49 more references View all →

Timeline

Published
Sep 16, 2021
Added to CISA KEV
Dec 1, 2021
Last Updated
Oct 27, 2025

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