Security readout for executives and security teams
Plain-English summary
This vulnerability can let an unauthenticated adjacent attacker cause Emerson DeltaV Distributed Control System controllers to restart, creating a denial-of-service condition. For an industrial site, the business issue is process disruption rather than data theft. The source bundle does not show confirmed exploitation or a specific patch.
Executive priority
Treat this as a moderate operational-resilience issue. It is not currently supported as actively exploited, but controller restarts can affect production availability. Prioritize sites using DeltaV and confirm vendor guidance before scheduling remediation work.
Technical view
CVE-2021-26264 is CWE-306, missing authentication for a critical function. The CVSS 3.1 score is 6.1 with adjacent-network attack vector, high attack complexity, no privileges, no user interaction, changed scope, and high availability impact. Structured affected-product metadata is incomplete, but the description names DeltaV DCS Controllers, all versions.
Likely exposure
Exposure is most relevant where DeltaV controllers are reachable from adjacent plant, engineering, or control networks. Internet-wide exposure is not supported by the CVSS vector or provided sources. Asset inventory should confirm any DeltaV controller presence because the bundled affected-product fields are marked n/a.
Exploitation context
The bundle says a specially crafted script could restart controllers and cause denial of service. CISA KEV status is false, and no provided source states active exploitation in the wild. High attack complexity and adjacent-network requirements reduce broad opportunistic risk but do not eliminate operational risk.
Researcher notes
The source bundle is thin: it names DeltaV DCS Controllers but lacks detailed CPEs, version ranges, exploit status, or fix text. Avoid assuming patch availability. Validation should focus on asset presence, network reachability, restart telemetry, and alignment with CISA or Emerson advisory updates.
Mitigation direction
- Review the CISA advisory and Emerson guidance for product-specific remediation or mitigations.
- Confirm whether Emerson has issued patches or configuration guidance for deployed DeltaV controller versions.
- Restrict controller access to trusted control-system networks while vendor guidance is reviewed.
- Monitor for unexpected controller restarts or availability events.
- Prioritize segmentation between enterprise, engineering, and controller networks.
Validation and detection
- Inventory DeltaV DCS controllers and record firmware or software versions.
- Check whether affected controllers are reachable from adjacent non-controller networks.
- Review operational logs for unexplained controller restarts or denial-of-service symptoms.
- Map compensating controls against the adjacent-network attack vector.
- Track remediation status against the CISA advisory reference.
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-306: Credential and account abuse lookup
Authentication and credential weaknesses can make valid-account abuse and credential telemetry useful review starting points. 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-2021-26264 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
- Medium
- CVSS
- 6.1 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/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:A/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H1.64Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
6.1MediumVector: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://www.cisa.gov/uscert/ics/advisories/icsa-21-355-04CVE 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.
Missing Authentication for Critical Function
Missing Authentication for Critical Function represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.