Security readout for executives and security teams
Plain-English summary
CVE-2026-27849 is a critical command-injection flaw in specific Linksys MR9600 and MX4200 firmware versions. An attacker could potentially run operating-system commands through the mesh-network update/configuration path. For organizations using these devices, priority is identifying affected firmware and limiting access until vendor guidance is confirmed.
Executive priority
Treat as urgent for environments using the listed Linksys models. The potential impact is full device compromise, but urgency depends on whether affected devices are deployed and reachable by untrusted parties.
Technical view
The CVE describes CWE-78 OS command injection caused by missing neutralization of special elements in update functionality over a TLS-SRP connection used for mesh configuration. Listed affected versions are MR9600 1.0.4.205530 and MX4200 1.0.13.210200. CVSS 3.1 is 9.8: network, low complexity, no privileges, no user interaction, high impact.
Likely exposure
Exposure is most relevant where affected Linksys mesh routers run the listed firmware and the TLS-SRP mesh update/configuration functionality is reachable from untrusted networks or devices. The sources do not confirm internet-wide exposure or default reachability from WAN.
Exploitation context
The CVE is public and has a third-party technical advisory. The source bundle does not identify active exploitation, and KEV is false. No exploit availability should be assumed from the provided evidence.
Researcher notes
The bundle contains a metadata inconsistency: MX4200 is listed with affected version 1.0.13.210200 while defaultStatus says unaffected. Validate against the CVE record, advisory, and vendor statements before final scoping. No patch details are included in the provided sources.
Mitigation direction
- Inventory Linksys MR9600 and MX4200 devices and record firmware versions.
- Check Linksys and the SYSS advisory for official firmware or mitigation guidance.
- Restrict management and mesh configuration access to trusted networks only.
- Segment affected devices from sensitive internal systems where feasible.
- Replace or remove affected devices if no vendor-supported remediation is available.
Validation and detection
- Confirm whether MR9600 runs 1.0.4.205530.
- Confirm whether MX4200 runs 1.0.13.210200.
- Verify mesh configuration/update services are not reachable from untrusted networks.
- Review device logs for unusual update or configuration activity.
- Track vendor advisories for corrected affected-version and fix information.
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-78: Command execution behavior lookup
Command injection weaknesses can lead defenders to review execution techniques and command interpreter telemetry. 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-2026-27849 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
- Critical
- CVSS
- 9.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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:H/I:H/A:H3.95.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
9.8CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://www.syss.de/fileadmin/dokumente/Publikationen/Advisories/SYSS-2025-011.txtCVE reference · third-party-advisory, technical-description
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.
Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.