CVE-2020-8617A logic error in code which checks TSIG validity can be used to trigger an assertion failure in tsig.c
- 7.5HighCVSS base score
- 93.3%Exploitation in 30 daysEPSS · top 0.2% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- 2Public exploitsMetasploit, Nuclei and Exploit-DB
Description
Using a specially-crafted message, an attacker may potentially cause a BIND server to reach an inconsistent state if the attacker knows (or successfully guesses) the name of a TSIG key used by the server. Since BIND, by default, configures a local session key even on servers whose configuration does not otherwise make use of it, almost all current BIND servers are vulnerable. In releases of BIND dating from March 2018 and after, an assertion check in tsig.c detects this inconsistent state and deliberately exits. Prior to the introduction of the check the server would continue operating in an inconsistent state, with potentially harmful results.
Public exploit
An exploit or proof of concept is public: anyone can try it against an unpatched system. The public collections list a Metasploit module and an Exploit-DB entry for it.
Show the exploits2
Metasploit modules1 module
- BIND TSIG Badtime Query Denial of Service (Metasploit module) (opens in a new tab)
auxiliary/dos/dns/bind_tsig_badtimeRank normaldisclosed 19 May 2020
Exploit-DB1 entry
- BIND - 'TSIG' Denial of Service (Exploit-DB entry) (opens in a new tab)
EDB-ID 48521dos, multiplepublished 20 May 2020Not verified
Modules, templates and exploits as listed by the Metasploit Framework (BSD-3-Clause), ProjectDiscovery's Nuclei templates (MIT) and the Exploit Database (GPLv2), read once a day. Where the data comes from
Timeline
ID reserved
By isc
- 3 months later
· 3 months later
Published
- 4 years later
· 4 years later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| iscCNA (assigner) | 3.1 | High7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| NVDNVD · Modified | 3.1 | Medium5.9 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 93.3% · top 0.2% of all CVEs (14 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.5.
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 known.
References
References12
- https://kb.isc.org/docs/cve-2020-8617 (opens in a new tab)x_refsource_CONFIRMx_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
- http://packetstormsecurity.com/files/157836/BIND-TSIG-Denial-Of-Service.html (opens in a new tab)x_refsource_MISCx_transferred
- USN-4365-2 (opens in a new tab)vendor-advisoryx_refsource_UBUNTUx_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)
- EUVD EUVD-2020-29465 (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://cveledger.app/cve/CVE-2020-8617)Record last updated .