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 2021-01-20 16:15:14
Updated 2022-12-08 03:08:51
Source Red Hat, Inc.
View at NVD,   CVE.org

Threat overview for CVE-2020-25685

Top countries where our scanners detected CVE-2020-25685
Top open port discovered on systems with this issue 53
IPs affected by CVE-2020-25685 854,018
Threat actors abusing to this issue? Yes
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Exploit prediction scoring system (EPSS) score for CVE-2020-25685

Probability of exploitation activity in the next 30 days: 0.39%

Percentile, the proportion of vulnerabilities that are scored at or less: ~ 70 % EPSS Score History EPSS FAQ

CVSS scores for CVE-2020-25685

Base Score Base Severity CVSS Vector Exploitability Score Impact Score Score Source
4.3
MEDIUM AV:N/AC:M/Au:N/C:N/I:P/A:N
8.6
2.9
NIST
3.7
LOW CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
2.2
1.4
NIST

CWE ids for CVE-2020-25685

  • The product stores or transmits sensitive data using an encryption scheme that is theoretically sound, but is not strong enough for the level of protection required.
    Assigned by:
    • nvd@nist.gov (Primary)
    • secalert@redhat.com (Secondary)

References for CVE-2020-25685

Products affected by CVE-2020-25685

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