Vulnerability Monitor

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CVE-2020-25685

A flaw was found in dnsmasq before version 2.83. When getting a reply from a forwarded query, dnsmasq checks in forward.c:reply_query(), which is the forwarded query that matches the reply, by only using a weak hash of the query name. Due to the weak hash (CRC32 when dnsmasq is compiled without DNSSEC, SHA-1 when it is) this flaw allows an off-path attacker to find several different domains all having the same hash, substantially reducing the number of attempts they would have to perform to forge a reply and get it accepted by dnsmasq. This is in contrast with RFC5452, which specifies that the query name is one of the attributes of a query that must be used to match a reply. This flaw could be abused to perform a DNS Cache Poisoning attack. If chained with CVE-2020-25684 the attack complexity of a successful attack is reduced. The highest threat from this vulnerability is to data integrity.

Published

2021-01-20T16:15:14.303

Last Modified

2024-11-21T05:18:27.807

Status

Modified

Source

[email protected]

Severity

CVSSv3.1: 3.7 (LOW)

CVSSv2 Vector

AV:N/AC:M/Au:N/C:N/I:P/A:N

  • Access Vector: NETWORK
  • Access Complexity: MEDIUM
  • Authentication: NONE
  • Confidentiality Impact: NONE
  • Integrity Impact: PARTIAL
  • Availability Impact: NONE
Exploitability Score

8.6

Impact Score

2.9

Weaknesses
  • Type: Secondary
    CWE-326
  • Type: Primary
    CWE-326
Affected Vendors & Products
Type Vendor Product Version/Range Vulnerable?
Application thekelleys dnsmasq < 2.83 Yes
Operating System fedoraproject fedora 32 Yes
Operating System fedoraproject fedora 33 Yes
Operating System debian debian_linux 10.0 Yes
Operating System arista eos < 4.21.14m Yes
Operating System arista eos < 4.22.9m Yes
Operating System arista eos < 4.23.7m Yes
Operating System arista eos < 4.24.5m Yes
Operating System arista eos < 4.25.2f Yes
References