CVE-2020-8616
BIND does not sufficiently limit the number of fetches performed when processing referrals
- Published
- Updated
- Reserved
- Assigned by
- isc
Description
A malicious actor who intentionally exploits this lack of effective limitation on the number of fetches performed when processing referrals can, through the use of specially crafted referrals, cause a recursing server to issue a very large number of fetches in an attempt to process the referral. This has at least two potential effects: The performance of the recursing server can potentially be degraded by the additional work required to perform these fetches, and The attacker can exploit this behavior to use the recursing server as a reflector in a reflection attack with a high amplification factor.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| iscCNA (assigner) | 3.1 | High8.6 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H |
| NVDNVD · Modified | 3.1 | High8.6 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 10.9% · top 4.1% of all CVEs (6 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 8.6.
Weakness
- In order for a server performing recursion to locate records in the DNS graph it must be capable of processing referrals, such as those received when it attempts to query an authoritative server for a record which is delegated elsewhere. In its original design BIND (as well as other nameservers) does not sufficiently limit the number of fetches which may be performed while processing a referral response. BIND 9.0.0 -> 9.11.18, 9.12.0 -> 9.12.4-P2, 9.14.0 -> 9.14.11, 9.16.0 -> 9.16.2, and releases 9.17.0 -> 9.17.1 of the 9.17 experimental development branch. All releases in the obsolete 9.13 and 9.15 development branches. All releases of BIND Supported Preview Edition from 9.9.3-S1 -> 9.11.18-S1.
- CWE-400 (opens in a new tab)All about CWE-400 and its CVEs
Affected products
- affected 9.0.0 -> 9.11.18, 9.12.0 -> 9.12.4-P2, 9.14.0 -> 9.14.11, 9.16.0 -> 9.16.2, and releases 9.17.0 -> 9.17.1 of the 9.17 experimental development branch. All releases in the obsolete 9.13 and 9.15 development branches. All releases of BIND Supported Preview Edition from 9.9.3-S1 -> 9.11.18-S1
What to do
Solution: Upgrade to the patched release most closely related to your current version of BIND: BIND 9.11.19 BIND 9.14.12 BIND 9.16.3 BIND Supported Preview Edition is a special feature preview branch of BIND provided to eligible ISC support customers. BIND 9.11.19-S1
Workaround: None
References (13)
- https://kb.isc.org/docs/cve-2020-8616 (opens in a new tab)x_refsource_CONFIRMx_transferred
- http://www.nxnsattack.com (opens in a new tab)x_refsource_MISCx_transferred
- [oss-security] 20200519 Two vulnerabilities disclosed in BIND (CVE-2020-8616 and CVE-2020-8617) (opens in a new tab)mailing-listx_refsource_MLISTx_transferred
- DSA-4689 (opens in a new tab)vendor-advisoryx_refsource_DEBIANx_transferred
- https://security.netapp.com/advisory/ntap-20200522-0002/ (opens in a new tab)x_refsource_CONFIRMx_transferred
- USN-4365-2 (opens in a new tab)vendor-advisoryx_refsource_UBUNTUx_transferred
- https://www.synology.com/security/advisory/Synology_SA_20_12 (opens in a new tab)x_refsource_CONFIRMx_transferred
- USN-4365-1 (opens in a new tab)vendor-advisoryx_refsource_UBUNTUx_transferred
- [debian-lts-announce] 20200530 [SECURITY] [DLA 2227-1] bind9 security update (opens in a new tab)mailing-listx_refsource_MLISTx_transferred
- FEDORA-2020-2d89cbcfd9 (opens in a new tab)vendor-advisoryx_refsource_FEDORAx_transferred
- FEDORA-2020-f9dcd4e9d5 (opens in a new tab)vendor-advisoryx_refsource_FEDORAx_transferred
- openSUSE-SU-2020:1699 (opens in a new tab)vendor-advisoryx_refsource_SUSEx_transferred
- openSUSE-SU-2020:1701 (opens in a new tab)vendor-advisoryx_refsource_SUSEx_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2020-8616)Record last updated .