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cve[email protected]CVE-2020-25685
HistoryJan 20, 2021 - 4:15 p.m.

CVE-2020-25685

2021-01-2016:15:14
CWE-326
web.nvd.nist.gov
498
12
cve-2020-25685
dnsmasq
vulnerability
dns
cache poisoning
off-path attacker
data integrity

CVSS2

4.3

Attack Vector

NETWORK

Attack Complexity

MEDIUM

Authentication

NONE

Confidentiality Impact

NONE

Integrity Impact

PARTIAL

Availability Impact

NONE

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

CVSS3

3.7

Attack Vector

NETWORK

Attack Complexity

HIGH

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

NONE

Integrity Impact

LOW

Availability Impact

NONE

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

AI Score

6

Confidence

Low

EPSS

0.012

Percentile

85.0%

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.

Affected configurations

Vulners
NVD
Node
dnsmasqdnsmasqRange2.83
VendorProductVersionCPE
dnsmasqdnsmasq*cpe:2.3:a:dnsmasq:dnsmasq:*:*:*:*:*:*:*:*

CNA Affected

[
  {
    "vendor": "n/a",
    "product": "dnsmasq",
    "versions": [
      {
        "version": "dnsmasq 2.83",
        "status": "affected"
      }
    ]
  }
]

Social References

More

CVSS2

4.3

Attack Vector

NETWORK

Attack Complexity

MEDIUM

Authentication

NONE

Confidentiality Impact

NONE

Integrity Impact

PARTIAL

Availability Impact

NONE

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

CVSS3

3.7

Attack Vector

NETWORK

Attack Complexity

HIGH

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

NONE

Integrity Impact

LOW

Availability Impact

NONE

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

AI Score

6

Confidence

Low

EPSS

0.012

Percentile

85.0%