CVE-2023-50868

Publication date 13 February 2024

Last updated 11 July 2025

Ubuntu priority

Medium

Why this priority?

Cvss 3 Severity Score

7.5 · High

Score breakdown

Description

The Closest Encloser Proof aspect of the DNS protocol (in RFC 5155 when RFC 9276 guidance is skipped) allows remote attackers to cause a denial of service (CPU consumption for SHA-1 computations) via DNSSEC responses in a random subdomain attack, aka the "NSEC3" issue. The RFC 5155 specification implies that an algorithm must perform thousands of iterations of a hash function in certain situations.

Read the notes from the security team

Status

Package Ubuntu Release Status
bind9 25.10 questing
Fixed 1:9.18.24-0ubuntu1
25.04 plucky
Fixed 1:9.18.24-0ubuntu1
24.10 oracular
Fixed 1:9.18.24-0ubuntu1
24.04 LTS noble
Fixed 1:9.18.24-0ubuntu1
23.10 mantic
Fixed 1:9.18.18-0ubuntu2.1
22.04 LTS jammy
Fixed 1:9.18.18-0ubuntu0.22.04.2
20.04 LTS focal
Fixed 1:9.16.48-0ubuntu0.20.04.1
18.04 LTS bionic
Fixed 1:9.11.3+dfsg-1ubuntu1.19+esm3
16.04 LTS xenial
Fixed 1:9.10.3.dfsg.P4-8ubuntu1.19+esm8
14.04 LTS trusty
Fixed 1:9.9.5.dfsg-3ubuntu0.19+esm12
isc-dhcp 25.10 questing
Needs evaluation
25.04 plucky
Needs evaluation
24.10 oracular Ignored end of life, was needs-triage
24.04 LTS noble
Needs evaluation
23.10 mantic Ignored end of life, was needs-triage
22.04 LTS jammy
Not affected
20.04 LTS focal
Not affected
18.04 LTS bionic
Not affected
16.04 LTS xenial
Not affected
14.04 LTS trusty
Not affected
unbound 25.10 questing
Fixed 1.19.1-1ubuntu1
25.04 plucky
Fixed 1.19.1-1ubuntu1
24.10 oracular
Fixed 1.19.1-1ubuntu1
24.04 LTS noble
Fixed 1.19.1-1ubuntu1
23.10 mantic
Fixed 1.17.1-2ubuntu0.1
22.04 LTS jammy
Fixed 1.13.1-1ubuntu5.4
20.04 LTS focal
Fixed 1.9.4-2ubuntu1.5
18.04 LTS bionic
Needs evaluation
16.04 LTS xenial
Needs evaluation
14.04 LTS trusty
Needs evaluation
pdns-recursor 25.10 questing
Not affected
25.04 plucky
Not affected
24.10 oracular
Not affected
24.04 LTS noble
Not affected
23.10 mantic Ignored end of life, was needs-triage
22.04 LTS jammy
Needs evaluation
20.04 LTS focal
Needs evaluation
18.04 LTS bionic
Needs evaluation
16.04 LTS xenial
Needs evaluation
14.04 LTS trusty Ignored end of standard support
dnsmasq 25.10 questing
Fixed 2.90-1
25.04 plucky
Fixed 2.90-1
24.10 oracular
Fixed 2.90-1
24.04 LTS noble
Fixed 2.90-1
23.10 mantic
Fixed 2.90-0ubuntu0.23.10.1
22.04 LTS jammy
Fixed 2.90-0ubuntu0.22.04.1
20.04 LTS focal
Fixed 2.90-0ubuntu0.20.04.1
18.04 LTS bionic
Fixed 2.90-0ubuntu0.18.04.1+esm1
16.04 LTS xenial
Fixed 2.90-0ubuntu0.16.04.1+esm1
14.04 LTS trusty Ignored changes too intrusive
knot-resolver 25.10 questing
Not affected
25.04 plucky
Not affected
24.10 oracular
Not affected
24.04 LTS noble
Not affected
23.10 mantic Ignored end of life, was needs-triage
22.04 LTS jammy
Needs evaluation
20.04 LTS focal
Needs evaluation
18.04 LTS bionic
Needs evaluation
16.04 LTS xenial
Needs evaluation
14.04 LTS trusty Not in release
bind9-libs 25.10 questing Not in release
25.04 plucky Not in release
24.10 oracular Not in release
24.04 LTS noble Not in release
23.10 mantic Not in release
22.04 LTS jammy
Needs evaluation
20.04 LTS focal
Needs evaluation
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release

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Notes

alexmurray

As of isc-dhcp-4.4.3-1, isc-dhcp vendors bind9 libs

mdeslaur

This is unlikely to affect isc-dhcp's use of bind9-libs and the vendored bind9 libs, marking as negligible

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package Patch details
unbound

Severity score breakdown

Parameter Value
Base score 7.5 · High
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Scope Unchanged
Confidentiality None
Integrity impact High
Availability impact None
Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

References

Related Ubuntu Security Notices (USN)

Other references