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CVE-2023-4408

Parsing large DNS messages may cause excessive CPU load

High7.5EPSS 1.4%
Published
Updated
Reserved
Assigned by
isc

Description

The DNS message parsing code in `named` includes a section whose computational complexity is overly high. It does not cause problems for typical DNS traffic, but crafted queries and responses may cause excessive CPU load on the affected `named` instance by exploiting this flaw. This issue affects both authoritative servers and recursive resolvers. This issue affects BIND 9 versions 9.0.0 through 9.16.45, 9.18.0 through 9.18.21, 9.19.0 through 9.19.19, 9.9.3-S1 through 9.11.37-S1, 9.16.8-S1 through 9.16.45-S1, and 9.18.11-S1 through 9.18.21-S1.

Scores

CVSS scores of CVE-2023-4408, by who scored it
Scored byCVSSScoreVector
iscCNA (assigner)3.1High7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVDNVD · Modified3.1High7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS (exploitation in 30 days)
1.4% · top 28% of all CVEs (6 Nov 2026)
CISA SSVC
Exploitation: none · Automatable: no · Technical impact: partial
Loading the EPSS history…

The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.5.

Weakness

Affected products

  • ISC · BIND 9

    • affected 9.0.0 – ≤ 9.16.45
    • affected 9.18.0 – ≤ 9.18.21
    • affected 9.19.0 – ≤ 9.19.19
    • affected 9.9.3-S1 – ≤ 9.11.37-S1
    • affected 9.16.8-S1 – ≤ 9.16.45-S1
    • affected 9.18.11-S1 – ≤ 9.18.21-S1

What to do

Solution: Upgrade to the patched release most closely related to your current version of BIND 9: 9.16.48, 9.18.24, 9.19.21, 9.16.48-S1, or 9.18.24-S1.

Workaround: No workarounds known.

Exploitation: We are not aware of any active exploits.

References (7)

Sources

The same CVE in the primary databases and aggregators, to check against.

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Record last updated .