Memory Overwrite Vulnerability in nginx Resolver by F5 Networks
CVE-2021-23017

7.7HIGH

Key Information:

Vendor
F5
Status
Nginx Web Server, Nginx Plus
Vendor
CVE Published:
1 June 2021

Badges

👾 Exploit Exists🟡 Public PoC🟣 EPSS 40%

Summary

A security flaw was identified in the nginx resolver that allows an attacker capable of forging UDP packets from a DNS server to exploit the vulnerability. This could lead to a 1-byte memory overwrite, potentially resulting in a crash of the worker process and causing disruptions or additional impacts on system performance.

Affected Version(s)

Nginx Web Server, Nginx Plus Nginx Web Server versions 0.6.18 thru 1.20.0 before 1.20.1, Nginx plus versions R13 thru R23 before R23 P1. Nginx plus version R24 before R24 P1

Exploit Proof of Concept (PoC)

PoC code is written by security researchers to demonstrate the vulnerability can be exploited. PoC code is also a key component for weaponization which could lead to ransomware.

CVE-2021-23017-PoC
Created by M507

nginx-patch
Created by niandy

CVE-2021-23017-POC
Created by z3usx01

References

https://support.f5.com/csp/article/K12331123%2C
x_refsource_MISC
http://mailman.nginx.org/pipermail/nginx-announce/2021/00...
x_refsource_MISC
https://lists.apache.org/thread.html/r6fc5c57b38e93e36213...
mailing-listx_refsource_MLIST

EPSS Score

40% chance of being exploited in the next 30 days.

CVSS V3.1

Score:
7.7
Severity:
HIGH
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
High
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • 🟡

    Public PoC available

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

.