A second vulnerability in BIND's GSSAPI security policy negotiation can be targeted by a buffer overflow attack
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.
- Published
- Apr 28, 2021
- Updated
- Jun 16, 2026
- EPSS
- 82.4% · 100th percentile
- CWE
- CWE-125
Sign in to follow · You’ll be notified if a followed record enters KEV, gets an exploit or is updated.
Report tools
Action score
64
This week
Don’t wait for the next maintenance window.
- CVSS
- 39 / 40 · 9.8 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 25 / 30 · 82.4%
CNA vs NVD score
- NVD
- 9.8
- CNA · isc
- 8.1
- 1.7 point gap
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| debian | debian linux | cpe:2.3:o:debian:debian_linux |
| isc | bind | cpe:2.3:a:isc:bind |
| siemens | sinec infrastructure network services | cpe:2.3:a:siemens:sinec_infrastructure_network_services |
| netapp | active iq unified manager | cpe:2.3:a:netapp:active_iq_unified_manager |
| netapp | cloud backup | cpe:2.3:a:netapp:cloud_backup |
| netapp | aff a250 firmware | cpe:2.3:o:netapp:aff_a250_firmware |
| netapp | aff a250 | cpe:2.3:h:netapp:aff_a250 |
| netapp | aff 500f firmware | cpe:2.3:o:netapp:aff_500f_firmware |
| netapp | aff 500f | cpe:2.3:h:netapp:aff_500f |
| netapp | h300s firmware | cpe:2.3:o:netapp:h300s_firmware |
| netapp | h300s | cpe:2.3:h:netapp:h300s |
| netapp | h500s firmware | cpe:2.3:o:netapp:h500s_firmware |
and 11 more
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- debian debian linux10.0
- debian debian linux9.0
- isc bind9.17.0 and later · before 9.17.12
- isc bind9.0.0 and later · before 9.11.31
- isc bind9.12.0 and later · before 9.16.15
- isc bind9.10.5
- isc bind9.10.7
- isc bind9.11.12
- isc bind9.11.21
- isc bind9.11.27
- isc bind9.11.29
- isc bind9.11.3
- isc bind9.11.5
- isc bind9.11.6
- isc bind9.11.7
- isc bind9.11.8
- isc bind9.16.11
- isc bind9.16.13
- isc bind9.16.8
- isc bind9.9.12
Versions reported by the vendor
Affected version ranges reported by the assigning authority (isc). Independent of NVD's CPE analysis and usually ahead of it.
ISC BIND9
- Open Source Branches 9.5 though 9.11 9.5.0 through versions before 9.11.31, Open Source Branches 9.12 though 9.16 9.12.0 through versions before 9.16.14, Supported Preview Branch 9.11-S 9.11.3-S1 through versions before 9.11.31-S1, Supported Preview Branch 9.16-S 9.16.8-S1 through versions before 9.16.14-S1, Development Branch 9.17 9.17.0 through versions before 9.17.2affected
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Alpine:v3.10 | bind | from 9.0.0 · before 9.16.15-r0 | 9.16.15-r0 |
| Debian:10 | bind9 | before 1:9.11.5.P4+dfsg-5.1+deb10u5 | 1:9.11.5.P4+dfsg-5.1+deb10u5 |
| Debian:12 | bind9 | before 1:9.16.15-1 | 1:9.16.15-1 |
| Debian:9 | bind9 | before 1:9.10.3.dfsg.P4-12.3+deb9u9 | 1:9.10.3.dfsg.P4-12.3+deb9u9 |
| SUSE:HPE Helion OpenStack 8 | bind | before 9.9.9P1-63.25.1 | 9.9.9P1-63.25.1 |
| SUSE:Linux Enterprise Point of Sale 11 SP3 | bind | before 9.9.6P1-0.51.26.1 | 9.9.6P1-0.51.26.1 |
Same product
debian: all recordsOther highest-scoring records for the same primary product.
- CVE-2016-9079A use-after-free vulnerability in SVG Animation has been discovered.KEV86Now
- CVE-2024-44308The issue was addressed with improved checks.KEV68This week
- CVE-2024-44309A cookie management issue was addressed with improved state management.KEV62This week
- CVE-2016-2098Action Pack in Ruby on Rails before 3.2.22.2, 4.x before 4.1.14.2, and 4.2.x before 4.2.5.2 allows remote attackers to execute arbitrary Rub53Plan
- CVE-2015-1592Movable Type Pro, Open Source, and Advanced before 5.2.12 and Pro and Advanced 6.0.x before 6.0.7 does not properly use the Perl Storable::t53Plan
- CVE-2016-2851Integer overflow in proto.c in libotr before 4.1.1 on 64-bit platforms allows remote attackers to cause a denial of service (memory corrupti47Plan
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| Alpine:bind | 9.16.15-r0 · Alpine:v3.10 | Package registry (OSV) |
| Debian:bind9 | 1:9.16.15-1 · Debian:12 | Package registry (OSV) |
| SUSE:bind | 9.9.9P1-63.25.1 · SUSE:HPE Helion OpenStack 8 | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- high · data can be read
- Integrity
- high · data or configuration can be modified
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- High
Weakness class (CWE)
CWE-125 · Out-of-bounds ReadCVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
ATT&CK techniques
—
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpChange log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- www.openwall.com/lists/oss-security/2021/04/29/1
- www.openwall.com/lists/oss-security/2021/04/29/2
- www.openwall.com/lists/oss-security/2021/04/29/3
- www.openwall.com/lists/oss-security/2021/04/29/4
- cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf
- kb.isc.org/v1/docs/cve-2021-25215
- lists.debian.org/debian-lts-announce/2021/05/msg00001.html
- security.netapp.com/advisory/ntap-20210521-0006/
- www.debian.org/security/2021/dsa-4909
- www.zerodayinitiative.com/advisories/ZDI-21-657/
Vendor advisories and official records. Exploit/PoC links are deliberately left out.