CVE-2021-43848
H2O HTTP/3 Server Uninitialized Memory Access Vulnerability
Description
h2o is an open source http server. In code prior to the `8c0eca3` commit h2o may attempt to access uninitialized memory. When receiving QUIC frames in certain order, HTTP/3 server-side implementation of h2o can be misguided to treat uninitialized memory as HTTP/3 frames that have been received. When h2o is used as a reverse proxy, an attacker can abuse this vulnerability to send internal state of h2o to backend servers controlled by the attacker or third party. Also, if there is an HTTP endpoint that reflects the traffic sent from the client, an attacker can use that reflector to obtain internal state of h2o. This internal state includes traffic of other connections in unencrypted form and TLS session tickets. This vulnerability exists in h2o server with HTTP/3 support, between commit 93af138 and d1f0f65. None of the released versions of h2o are affected by this vulnerability. There are no known workarounds. Users of unreleased versions of h2o using HTTP/3 are advised to upgrade immediately.
INFO
Published Date :
Feb. 1, 2022, 1:15 p.m.
Last Modified :
Feb. 7, 2022, 9:11 p.m.
Source :
[email protected]
Remotely Exploitable :
Yes !
Impact Score :
5.2
Exploitability Score :
2.2
Public PoC/Exploit Available at Github
CVE-2021-43848 has a 5 public PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2021-43848.
| URL | Resource |
|---|---|
| https://github.com/h2o/h2o/commit/8c0eca3 | Patch Third Party Advisory |
| https://github.com/h2o/h2o/security/advisories/GHSA-f9xw-j925-m4m4 | Third Party Advisory |
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
All CVE - PoC in GitHub
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None
None
None
exploit for CVE-2021-43848
Go Dockerfile Shell
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2021-43848 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2021-43848 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by [email protected]
May. 14, 2024
Action Type Old Value New Value -
Initial Analysis by [email protected]
Feb. 07, 2022
Action Type Old Value New Value Added CVSS V2 NIST (AV:N/AC:M/Au:N/C:P/I:N/A:N) Added CVSS V3.1 NIST AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N Changed Reference Type https://github.com/h2o/h2o/commit/8c0eca3 No Types Assigned https://github.com/h2o/h2o/commit/8c0eca3 Patch, Third Party Advisory Changed Reference Type https://github.com/h2o/h2o/security/advisories/GHSA-f9xw-j925-m4m4 No Types Assigned https://github.com/h2o/h2o/security/advisories/GHSA-f9xw-j925-m4m4 Third Party Advisory Added CPE Configuration OR *cpe:2.3:a:dena:h2o:*:*:*:*:*:*:*:* versions up to (excluding) 2021-12-20
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2021-43848 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2021-43848
weaknesses.
Exploit Prediction
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days.
0.15 }} 0.01%
score
0.51683
percentile