CVE-2021-21294
Http4s Blaze Server Denial of Service
Description
Http4s (http4s-blaze-server) is a minimal, idiomatic Scala interface for HTTP services. Http4s before versions 0.21.17, 0.22.0-M2, and 1.0.0-M14 have a vulnerability which can lead to a denial-of-service. Blaze-core, a library underlying http4s-blaze-server, accepts connections unboundedly on its selector pool. This has the net effect of amplifying degradation in services that are unable to handle their current request load, since incoming connections are still accepted and added to an unbounded queue. Each connection allocates a socket handle, which drains a scarce OS resource. This can also confound higher level circuit breakers which work based on detecting failed connections. http4s provides a general "MaxActiveRequests" middleware mechanism for limiting open connections, but it is enforced inside the Blaze accept loop, after the connection is accepted and the socket opened. Thus, the limit only prevents the number of connections which can be simultaneously processed, not the number of connections which can be held open. In 0.21.17, 0.22.0-M2, and 1.0.0-M14, a new "maxConnections" property, with a default value of 1024, has been added to the `BlazeServerBuilder`. Setting the value to a negative number restores unbounded behavior, but is strongly disrecommended. The NIO2 backend does not respect `maxConnections`. Its use is now deprecated in http4s-0.21, and the option is removed altogether starting in http4s-0.22. There are several possible workarounds described in the refrenced GitHub Advisory GHSA-xhv5-w9c5-2r2w.
INFO
Published Date :
Feb. 2, 2021, 10:15 p.m.
Last Modified :
Oct. 24, 2022, 8:48 p.m.
Source :
[email protected]
Remotely Exploitable :
Yes !
Impact Score :
3.6
Exploitability Score :
3.9
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-2021-21294
.
URL | Resource |
---|---|
https://github.com/http4s/blaze/security/advisories/GHSA-xmw9-q7x9-j5qc | Third Party Advisory |
https://github.com/http4s/http4s/commit/987d6589ef79545b9bb2324ac4bdebf82d9a0171 | Patch Third Party Advisory |
https://github.com/http4s/http4s/security/advisories/GHSA-xhv5-w9c5-2r2w | 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).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2021-21294
vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2021-21294
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 -
Reanalysis by [email protected]
Oct. 24, 2022
Action Type Old Value New Value Added CWE NIST CWE-770 -
Initial Analysis by [email protected]
Feb. 08, 2021
Action Type Old Value New Value Added CVSS V2 NIST (AV:N/AC:L/Au:N/C:N/I:N/A:P) Added CVSS V3.1 NIST AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Changed Reference Type https://github.com/http4s/blaze/security/advisories/GHSA-xmw9-q7x9-j5qc No Types Assigned https://github.com/http4s/blaze/security/advisories/GHSA-xmw9-q7x9-j5qc Third Party Advisory Changed Reference Type https://github.com/http4s/http4s/commit/987d6589ef79545b9bb2324ac4bdebf82d9a0171 No Types Assigned https://github.com/http4s/http4s/commit/987d6589ef79545b9bb2324ac4bdebf82d9a0171 Patch, Third Party Advisory Changed Reference Type https://github.com/http4s/http4s/security/advisories/GHSA-xhv5-w9c5-2r2w No Types Assigned https://github.com/http4s/http4s/security/advisories/GHSA-xhv5-w9c5-2r2w Third Party Advisory Added CPE Configuration OR *cpe:2.3:a:typelevel:http4s:*:*:*:*:*:*:*:* versions up to (excluding) 0.21.17
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2021-21294
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-2021-21294
weaknesses.
Exploit Prediction
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days.
0.15 }} 0.02%
score
0.50465
percentile