Security readout for executives and security teams
Plain-English summary
A memory-safety flaw in BIND 9’s DNS-over-HTTPS implementation can be triggered remotely without authentication. Successful exploitation could expose sensitive process memory or crash the DNS service. Exploitation is considered difficult, but affected internet-facing DNS-over-HTTPS services warrant prompt remediation.
Executive priority
Treat as a high-priority patching issue for exposed DNS-over-HTTPS infrastructure because compromise could disclose memory or disrupt DNS availability. Accelerate remediation for public services; validate internal deployments during the normal urgent-vulnerability cycle. Current evidence does not justify declaring an active-exploitation emergency.
Technical view
CVE-2026-3593 is a heap use-after-free, classified as CWE-416 and CWE-825. It affects BIND 9.20.0–9.20.22, 9.21.0–9.21.21, and 9.20.9-S1–9.20.22-S1. CVSS 3.1 is 7.4: network-accessible, high complexity, unauthenticated, no user interaction, with high confidentiality and availability impact but no stated integrity impact.
Likely exposure
Exposure is most likely where an affected BIND 9 release uses a remotely reachable DNS-over-HTTPS implementation. BIND 9.18.0–9.18.48 and 9.18.11-S1–9.18.48-S1 are explicitly unaffected. The supplied evidence does not define additional configuration prerequisites.
Exploitation context
The CVSS assessment indicates remote, unauthenticated exploitation but high attack complexity. The source bundle does not identify public exploitation, and the CVE is not listed as KEV. Absence from KEV is not proof that exploitation has never occurred.
Researcher notes
The supplied data establishes the affected ranges and CVSS impacts but does not describe the triggering request pattern, required runtime state, exploit reliability, or observed attacks. Testing should remain defensive and controlled. Do not infer that all BIND installations are exposed merely from their version; confirm DNS-over-HTTPS use and network reachability.
Mitigation direction
- Upgrade 9.20 deployments to BIND 9.20.23 or a later vendor-supported fixed release.
- Upgrade 9.21 deployments to BIND 9.21.22 or a later vendor-supported fixed release.
- For affected S1 releases, consult ISC guidance for the appropriate supported fixed version.
- Prioritize externally reachable DNS-over-HTTPS services and apply vendor or distribution security updates.
Validation and detection
- Inventory BIND versions across authoritative, recursive, proxy, container, and appliance deployments.
- Confirm whether DNS-over-HTTPS is enabled and reachable from untrusted networks.
- Verify installed versions fall outside the affected ranges after remediation.
- Confirm BIND 9.18 deployments remain within the explicitly unaffected ranges stated by ISC.
- Review service health and crash telemetry for unexplained BIND failures.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-416: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCWE-825: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2026-3593 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 7.4 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
2 official scoresWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H2.25.2iscCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H2.25.2redhat-SADPVulnerability scoring details
Base CVSS 3.1 score
7.4HighVector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H
Base CVSS 3.1 score
7.4HighVector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- ADP timelineredhat-SADP
Reported to Red Hat.
- CVE publishedCVE Program
The CVE record was published.
- ADP timelineredhat-SADP
Made public.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
- 2026-05-19T09:55:25.800Z: Reported to Red Hat.
- 2026-05-21T11:59:02.348Z: Made public.
Source materials
- CVE List V5 sourceCVE List V5
- CVE-2026-3593CVE reference, isc · vendor-advisory
- https://downloads.isc.org/isc/bind9/9.20.23CVE reference, isc · patch
- https://downloads.isc.org/isc/bind9/9.21.22CVE reference, isc · patch
- https://access.redhat.com/security/cve/CVE-2026-3593CVE reference, redhat-SADP · vdb-entry, x_refsource_REDHAT
- RHBZ#2479770CVE reference, redhat-SADP · issue-tracking, x_refsource_REDHAT
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-3593.jsonCVE reference, redhat-SADP · x_sadp-csaf-vex
- https://access.redhat.com/errata/RHSA-2026:7412CVE reference, redhat-SADP · vendor-advisory, x_refsource_REDHAT
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Use After Free
Use After Free represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Expired Pointer Dereference
Expired Pointer Dereference represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.