1972881 – (CVE-2021-34549) CVE-2021-34549 tor: hashtable-based CPU denial-of-service attack against relays

Bug 1972881 (CVE-2021-34549) - CVE-2021-34549 tor: hashtable-based CPU denial-of-service attack against relays

Summary: CVE-2021-34549 tor: hashtable-based CPU denial-of-service attack against relays

Keywords:
Status:	CLOSED UPSTREAM
Alias:	CVE-2021-34549
Product:	Security Response
Classification:	Other
Component:	vulnerability
Sub Component:
Version:	unspecified
Hardware:	All
OS:	Linux
Priority:	medium
Severity:	medium
Target Milestone:	---
Assignee:	Red Hat Product Security
QA Contact:
Docs Contact:
URL:
Whiteboard:
Depends On:	1972882 1972883
Blocks:
TreeView+	depends on / blocked

Reported:	2021-06-16 19:41 UTC by Guilherme de Almeida Suckevicz
Modified:	2021-06-16 21:04 UTC (History)
CC List:	6 users (show)
Fixed In Version:
Doc Type:	If docs needed, set a value
Doc Text:
Clone Of:
Environment:
Last Closed:	2021-06-16 21:04:50 UTC
Embargoed:

Attachments	(Terms of Use)

Description Guilherme de Almeida Suckevicz 2021-06-16 19:41:52 UTC

Resist a hashtable-based CPU denial-of-service attack against relays. Previously we used a naive unkeyed hash function to look up circuits in a circuitmux object. An attacker could exploit this to construct circuits with chosen circuit IDs, to create collisions and make the hash table inefficient. Now we use a SipHash construction here instead. Fixes bug 40391; bugfix on 0.2.4.4-alpha. This issue is also tracked as TROVE-2021-005 and CVE-2021-34549.

References:
https://lists.torproject.org/pipermail/tor-announce/2021-June/000220.html
https://lists.torproject.org/pipermail/tor-announce/2021-June/000221.html

Comment 1 Guilherme de Almeida Suckevicz 2021-06-16 19:42:57 UTC

Created tor tracking bugs for this issue:

Affects: epel-all [bug 1972883]
Affects: fedora-all [bug 1972882]

Comment 2 Product Security DevOps Team 2021-06-16 21:04:50 UTC

This CVE Bugzilla entry is for community support informational purposes only as it does not affect a package in a commercially supported Red Hat product. Refer to the dependent bugs for status of those individual community products.

Note You need to log in before you can comment on or make changes to this bug.