Memory leak in code preparing DNSSEC proofs of non-existence
Summary
| CVE | CVE-2026-3104 |
|---|---|
| State | PUBLISHED |
| Assigner | isc |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-03-25 14:16:36 UTC |
| Updated | 2026-07-15 02:20:58 UTC |
| Description | A specially crafted domain can be used to cause a memory leak in a BIND resolver simply by querying this domain. This issue affects BIND 9 versions 9.20.0 through 9.20.20, 9.21.0 through 9.21.19, and 9.20.9-S1 through 9.20.20-S1. BIND 9 versions 9.18.0 through 9.18.46 and 9.18.11-S1 through 9.18.46-S1 are NOT affected. |
Risk And Classification
Primary CVSS: v3.1 7.5 HIGH from ADP
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Problem Types: CWE-772 | CWE-401 | CWE-772 CWE-772 Missing Release of Resource after Effective Lifetime | CWE-772 Missing Release of Resource after Effective Lifetime
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | ADP | CVSS | 7.5 | HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| 3.1 | [email protected] | Secondary | 7.5 | HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| 3.1 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | Secondary | 7.5 | HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| 3.1 | CNA | DECLARED | 7.5 | HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
CVSS v3.1 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD Known Affected Configurations (CPE 2.3)
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | ISC | BIND 9 | affected 9.20.0 9.20.20 custom | Not specified |
| CNA | ISC | BIND 9 | affected 9.21.0 9.21.19 custom | Not specified |
| CNA | ISC | BIND 9 | affected 9.20.9-S1 9.20.20-S1 custom | Not specified |
| CNA | ISC | BIND 9 | unaffected 9.18.0 9.18.46 custom | Not specified |
| CNA | ISC | BIND 9 | unaffected 9.18.11-S1 9.18.46-S1 custom | Not specified |
| ADP | Red Hat | Red Hat Hardened Images | unaffected 9.18.48-1.hum1 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 10 | Not specified | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 6 | Not specified | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 7 | Not specified | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 8 | Not specified | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 8 | Not specified | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 9 | Not specified | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 9 | Not specified | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 9 | Not specified | Not specified |
| ADP | Red Hat | Red Hat OpenShift Container Platform 4 | Not specified | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-3104.json | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | security.access.redhat.com | |
| downloads.isc.org/isc/bind9/9.20.21 | [email protected] | downloads.isc.org | Patch |
| downloads.isc.org/isc/bind9/9.21.20 | [email protected] | downloads.isc.org | Patch |
| kb.isc.org/docs/cve-2026-3104 | [email protected] | kb.isc.org | Vendor Advisory |
| bugzilla.redhat.com/show_bug.cgi | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | bugzilla.redhat.com | |
| access.redhat.com/security/cve/CVE-2026-3104 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:6935 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: ISC would like to thank Vitaly Simonovich for bringing this vulnerability to our attention. (en)
Additional Advisory Data
| Source | Time | Event |
|---|---|---|
| ADP | 2026-03-25T14:02:15.067Z | Reported to Red Hat. |
| ADP | 2026-03-25T13:29:19.494Z | Made public. |
Solutions
CNA: Upgrade to the patched release most closely related to your current version of BIND 9: 9.20.21, 9.21.20, or 9.20.21-S1.
ADP: RHSA-2026:6935: Red Hat Hardened Images
Workarounds
CNA: No workarounds known.
ADP: To mitigate this issue, restrict access to the BIND resolver to trusted clients only. This can be achieved by configuring firewall rules to limit inbound connections to port 53 (UDP/TCP) from known, authorized IP addresses or networks. Alternatively, configure BIND to listen only on specific trusted interfaces or localhost. Example using firewalld: `firewall-cmd --permanent --add-rich-rule='rule family="ipv4" source address="<TRUSTED_IP_OR_NETWORK>" port port=53 protocol="udp" accept'` `firewall-cmd --permanent --add-rich-rule='rule family="ipv4" source address="<TRUSTED_IP_OR_NETWORK>" port port=53 protocol="tcp" accept'` `firewall-cmd --reload` After applying changes, a restart of the BIND service may be required for the new configuration to take full effect. This may temporarily interrupt DNS resolution services.
Exploits
CNA: We are not aware of any active exploits.