CVE-2021-25216
What it is
In BIND 9.5.0 -> 9.11.29, 9.12.0 -> 9.16.13, and versions BIND 9.11.3-S1 -> 9.11.29-S1 and 9.16.8-S1 -> 9.16.13-S1 of BIND Supported Preview Edition, as well as release versions 9.17.0 -> 9.17.1 of the BIND 9.17 development branch, BIND servers are vulnerable if they are running an affected version and are configured to use GSS-TSIG features. In a configuration which uses BIND's default settings the vulnerable code path is not exposed, but a server can be rendered vulnerable by explicitly setting values for the tkey-gssapi-keytab or tkey-gssapi-credential configuration options. Although the default configuration is not vulnerable, GSS-TSIG is frequently used in networks where BIND is integrated with Samba, as well as in mixed-server environments that combine BIND servers with Active Directory domain controllers. For servers that meet these conditions, the ISC SPNEGO implementation is vulnerable to various attacks, depending on the CPU architecture for which BIND was built: For named binaries compiled for 64-bit platforms, this flaw can be used to trigger a buffer over-read, leading to a server crash. For named binaries compiled for 32-bit platforms, this flaw can be used to trigger a server crash due to a buffer overflow and possibly also to achieve remote code execution. We have determined that standard SPNEGO implementations are available in the MIT and Heimdal Kerberos libraries, which support a broad range of operating systems, rendering the ISC implementation unnecessary and obsolete. Therefore, to reduce the attack surface for BIND users, we will be removing the ISC SPNEGO implementation in the April releases of BIND 9.11 and 9.16 (it had already been dropped from BIND 9.17). We would not normally remove something from a stable ESV (Extended Support Version) of BIND, but since system libraries can replace the ISC SPNEGO implementation, we have made an exception in this case for reasons of stability and security.
At a glance
- Exploitability
- Can be exploited over the network without logging in. High risk of data exposure, data tampering, service disruption.
- Exploit odds
- 83.0% chance of exploitation in the next 30 days (EPSS). Higher than most.
- Fix
- A patch, advisory or fixed version is referenced. Upgrade or apply it.
Timeline
- ReservedThe CVE id was reserved by its CNA
- PublishedDisclosed publicly on CVE.org and NVD
- Last updatedMost recent change to the record
Why it ranks here
- Exploited in the wild: no, CISA does not list it.
- Exploit odds: 83.0% in the next 30 days (EPSS).
- Severity: 8.1 HIGH (CVSS).
- Fix: a patch or advisory is linked.
Details
- Published
- Last modified
- Exploit probability
- 83.0% · EPSS, next 30 days
- Weakness
- CWE-125 · Out-of-bounds read
- Record status
- Modified
Affected
- Debian Linux 9.0
- Debian Linux 10.0
- Isc Bind < 9.11.31
- Isc Bind < 9.16.15
- Isc Bind < 9.17.12
- Isc Bind 9.9.3
- Isc Bind 9.9.12
- Isc Bind 9.9.13
Attack profile CVSS 3.1 · 8.1
- Attack vector
- Network
- Complexity
- High
- Privileges needed
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Raw vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Is it in your code?
Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.
Read https://cve-list.com/agent/cve/CVE-2021-25216.md and follow it. Check whether this project is affected by CVE-2021-25216. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.
Fix and advisories
- https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf
- https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf
References
- http://www.openwall.com/lists/oss-security/2021/04/29/1
- http://www.openwall.com/lists/oss-security/2021/04/29/2
- http://www.openwall.com/lists/oss-security/2021/04/29/3
- http://www.openwall.com/lists/oss-security/2021/04/29/4
- https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf
- https://kb.isc.org/v1/docs/cve-2021-25215
- https://lists.debian.org/debian-lts-announce/2021/05/msg00001.html
- https://security.netapp.com/advisory/ntap-20210521-0006/
- https://www.debian.org/security/2021/dsa-4909
- https://www.zerodayinitiative.com/advisories/ZDI-21-657/
- http://www.openwall.com/lists/oss-security/2021/04/29/1
- http://www.openwall.com/lists/oss-security/2021/04/29/2
- http://www.openwall.com/lists/oss-security/2021/04/29/3
- http://www.openwall.com/lists/oss-security/2021/04/29/4
- https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf
- https://kb.isc.org/v1/docs/cve-2021-25215
- https://lists.debian.org/debian-lts-announce/2021/05/msg00001.html
- https://security.netapp.com/advisory/ntap-20210521-0006/
- https://www.debian.org/security/2021/dsa-4909
- https://www.zerodayinitiative.com/advisories/ZDI-21-657/