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Vulnerability Details : CVE-2021-43848

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.
Publish Date : 2022-02-01 Last Update Date : 2022-02-07
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- CVSS Scores & Vulnerability Types

CVSS Score
4.3
Confidentiality Impact Partial (There is considerable informational disclosure.)
Integrity Impact None (There is no impact to the integrity of the system)
Availability Impact None (There is no impact to the availability of the system.)
Access Complexity Medium (The access conditions are somewhat specialized. Some preconditions must be satistified to exploit)
Authentication Not required (Authentication is not required to exploit the vulnerability.)
Gained Access None
Vulnerability Type(s)
CWE ID 908

- Products Affected By CVE-2021-43848

# Product Type Vendor Product Version Update Edition Language
1 Application Dena H2O * * * * Version Details Vulnerabilities

- Number Of Affected Versions By Product

Vendor Product Vulnerable Versions
Dena H2O 1

- References For CVE-2021-43848

https://github.com/h2o/h2o/commit/8c0eca3
https://github.com/h2o/h2o/security/advisories/GHSA-f9xw-j925-m4m4 CONFIRM

- Metasploit Modules Related To CVE-2021-43848

There are not any metasploit modules related to this CVE entry (Please visit www.metasploit.com for more information)
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