CVE: CVE-2024-12705
Title: DNS-over-HTTPS implementation suffers from multiple issues under heavy query load
Document version: 2.0
Posting date: 29 January 2025
Program impacted: BIND 9
Versions affected:
BIND
- 9.18.0 -> 9.18.32
- 9.20.0 -> 9.20.4
- 9.21.0 -> 9.21.3
(Versions prior to 9.18.27 were not assessed.)
BIND Supported Preview Edition
- 9.18.11-S1 -> 9.18.32-S1
(Versions prior to 9.18.27-S1 were not assessed.)
Severity: High
Exploitable: Remotely
Description:
Clients using DNS-over-HTTPS (DoH) can exhaust a DNS resolver's CPU and/or memory by flooding it with crafted valid or invalid HTTP/2 traffic.
Impact:
By flooding a target resolver with HTTP/2 traffic and exploiting this flaw, an attacker could overwhelm the server, causing high CPU and/or memory usage and preventing other clients from establishing DoH connections. This would significantly impair the resolver's performance and effectively deny legitimate clients access to the DNS resolution service.
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Authoritative servers are affected by this vulnerability.
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Resolvers are affected by this vulnerability.
CVSS Score: 7.5
CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
For more information on the Common Vulnerability Scoring System and to obtain your specific environmental score please visit: https://nvd.nist.gov/vuln-metrics/cvss/v3-calculator?vector=AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H&version=3.1.
Workarounds:
The issue affects only the DNS-over-HTTPS protocol and does not apply to instances where DoH is not enabled.
Active exploits:
We are not aware of any active exploits.
Solution:
Upgrade to the patched release most closely related to your current version of BIND 9:
- 9.18.33
- 9.20.5
- 9.21.4
BIND Supported Preview Edition is a special feature preview branch of BIND provided to eligible ISC support customers.
- 9.18.33-S1
Acknowledgments:
ISC would like to thank Jean-François Billaud for bringing this vulnerability to our attention.
Document revision history:
- 1.0 Early Notification, 22 January 2025
- 2.0 Public disclosure, 29 January 2025
Related documents:
See our BIND 9 Security Vulnerability Matrix for a complete listing of security vulnerabilities and versions affected.
Do you still have questions? Questions regarding this advisory should be mailed to bind-security@isc.org or posted as confidential GitLab issues at https://gitlab.isc.org/isc-projects/bind9/-/issues/new?issue[confidential]=true.
Note:
ISC patches only currently supported versions. When possible we indicate EOL versions affected. For current information on which versions are actively supported, please see https://www.isc.org/download/.
ISC Security Vulnerability Disclosure Policy:
Details of our current security advisory policy and practice can be found in the ISC Software Defect and Security Vulnerability Disclosure Policy at https://kb.isc.org/docs/aa-00861.
The Knowledgebase article https://kb.isc.org/docs/cve-2024-12705 is the complete and official security advisory document.
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