Security readout for executives and security teams
Plain-English summary
CVE-2026-27831 affects rldns, an open source DNS server. Version 1.3 can crash from a heap out-of-bounds read, causing denial of service. For organizations using rldns 1.3, the business risk is DNS service disruption. The source bundle states version 1.4 contains the patch.
Executive priority
Treat as a near-term availability issue if rldns is used. Patch affected DNS servers promptly, because DNS outages can interrupt applications, users, and dependent services. If rldns is not present, no direct action is indicated beyond documenting non-exposure.
Technical view
rldns 1.3 has CWE-125 heap-based out-of-bounds read. The CVSS 3.1 vector is AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H, indicating unauthenticated network-triggerable availability impact. The provided record names only bluedragonsecurity rldns version 1.3 as affected and says rldns 1.4 fixes the issue.
Likely exposure
Exposure is likely limited to environments running bluedragonsecurity rldns version 1.3, especially if the DNS service is reachable over a network. The sources do not identify other affected versions, packages, or downstream distributions.
Exploitation context
The CVSS vector indicates remote, unauthenticated, low-complexity denial of service is possible. The provided KEV flag is false, and the supplied sources do not establish active exploitation. Public references include an advisory, a fix-related repository, a diff, and a write-up.
Researcher notes
Evidence is concise: affected product is bluedragonsecurity rldns, affected version is exactly 1.3, fixed version is 1.4. The weakness is CWE-125 with availability-only impact. Do not assume confidentiality or integrity impact from the provided data. No KEV listing or cited active exploitation evidence is present.
Mitigation direction
- Upgrade rldns 1.3 deployments to rldns 1.4 or later per vendor guidance.
- Prioritize internet-facing or business-critical DNS servers first.
- If upgrade timing is uncertain, check the GitHub advisory for current vendor instructions.
- Ensure DNS service monitoring can detect crashes or availability drops.
Validation and detection
- Inventory DNS servers and confirm whether rldns is installed.
- Verify installed rldns versions; flag any version 1.3 instances.
- Confirm upgraded systems report rldns 1.4 or a vendor-fixed build.
- Review service logs and monitoring for unexplained rldns crashes.
- Track the CVE and GitHub advisory for updated affected-version guidance.
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-125: 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-2026-27831 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
- 7.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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.
CVSS vector scores
1 official scoreWe 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:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.5HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/bluedragonsecurity/rldns/security/advisories/GHSA-fv38-45j4-g9x4CVE reference · x_refsource_CONFIRM
- https://github.com/bluedragonsecurity/rldns-1.3-heap-out-of-bounds-vulnerability-fixed-in-rldns-1.4CVE reference · x_refsource_MISC
- https://github.com/bluedragonsecurity/rldns_archives/blob/main/diff/rldns-1.4.diffCVE reference · x_refsource_MISC
- https://medium.com/@w1sdom/heap-based-buffer-over-read-vulnerability-in-rldns-1-3-5da3bccdc031CVE reference · x_refsource_MISC
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.
Out-of-bounds Read
Out-of-bounds Read represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.