Vulnerability · Published Feb 1, 2022 · Assigned by GitHub_M
CVE-2021-43848Unititialized memory access in h2o
High 7.4
In plain English
A high-severity security flaw in h2o from h2o. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 2.7% (higher than 86% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu:24.04:LTS | h2o | no fix listed | UBUNTU-CVE-2021-43848 |
Affected products (as reported)
Weakness: CWE-908 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H
References
- https://github.com/h2o/h2o/security/advisories/GHSA-f9xw-j925-m4m4 x_refsource_CONFIRM
- https://github.com/h2o/h2o/commit/8c0eca3 x_refsource_MISC