A logic error in code which checks TSIG validity can be used to trigger an assertion failure in tsig.c

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.

Scores

EPSS (exploitation in 30 days)

93.3% · top 0.2% of all CVEs (7 Nov 2026)

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

Weakness

• An error in BIND code which checks the validity of messages containing TSIG resource records can be exploited by an attacker to trigger an assertion failure in tsig.c, resulting in denial of service to clients. 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-617 (opens in a new tab)All about CWE-617 and its CVEs

Affected products

• ISC · BIND9

  • 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 (12)

• 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)
• 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

[![CVE-2020-8617](https://trackcve.app/badge/CVE-2020-8617.svg)](https://trackcve.app/cve/CVE-2020-8617)

Record last updated 16 Sept 2024, 20:26 UTC.