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SCA: security update for org.http4s:http4s-blaze-server_2.12, org.http4s:http4s-blaze-server_2.13 (GHSA-xhv5-w9c5-2r2w)
high Tenable Cloud Security Plugin ID 420532
Description
There are packages installed that are affected by a vulnerability referenced in the following CVE:- 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.
(CVE-2021-21294)
See Also
Plugin Details
Severity: High
ID: 420532
Version: Revision 1.4
Type: Local
Family: SCA Checks
Published: 1/23/2025
Updated: 7/2/2026
Supported Sensors: Tenable Cloud Security, Tenable Self-Hosted Container Security
Risk Information
VPR
Risk Factor: Low
Score: 3
Percentile: 23.18
Vendor
Vendor Severity: High
CVSS v2
Risk Factor: Medium
Base Score: 5
Temporal Score: 3.7
Vector: CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:P
CVSS Score Source: CVE-2021-21294
CVSS v3
Risk Factor: High
Base Score: 7.5
Temporal Score: 6.5
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C
Vulnerability Information
Exploit Ease: No known exploits are available
Patch Publication Date: 2/2/2021
Vulnerability Publication Date: 2/2/2021
Reference Information
CVE: CVE-2021-21294