Security readout for executives and security teams
Plain-English summary
CVE-2021-36603 is a browser-side script injection flaw in Tasmota firmware 6.5.0. A crafted value in the “Friendly Name 1” field can run JavaScript when viewed, potentially exposing browser-session data or altering page behavior. The published severity is medium, and no active exploitation is cited.
Executive priority
Treat this as a moderate-priority exposure-management issue. It is unlikely to justify emergency response by itself, but internet-exposed or broadly accessible device administration interfaces should be tightened quickly because the flaw can affect administrator browser sessions.
Technical view
The CVE describes stored XSS, CWE-79, in Tasmota firmware 6.5.0 via the “Friendly Name 1” field. CVSS 3.1 is 6.1: network reachable, low complexity, no privileges, user interaction required, changed scope, low confidentiality and integrity impact, no availability impact.
Likely exposure
Exposure is most relevant where Tasmota 6.5.0 devices are deployed and their web interface or configuration pages are reachable by users. The source bundle’s affected vendor/product fields are incomplete, so teams should validate device firmware versions directly rather than relying only on CPE inventory.
Exploitation context
The CVE source supports remote XSS through a crafted field value, with user interaction required by the CVSS vector. It is not listed in KEV, and the provided sources do not claim active exploitation, public weaponization, or exploitation in the wild.
Researcher notes
Evidence is limited. The CVE identifies Tasmota firmware 6.5.0 and the vulnerable field, but the structured affected product data is “n/a” and no fix is named in the provided bundle. Do not assume broader version impact without vendor confirmation.
Mitigation direction
- Check Tasmota vendor guidance and the linked issue for fixed-version information.
- Restrict Tasmota web interfaces to trusted management networks only.
- Remove unexpected or untrusted values from the Friendly Name 1 field.
- Upgrade affected devices if vendor documentation identifies a fixed release.
- Avoid exposing device administration interfaces to the public internet.
Validation and detection
- Inventory Tasmota devices and confirm whether firmware 6.5.0 is present.
- Review Friendly Name 1 values for unexpected script-like or untrusted content.
- Confirm device web interfaces are not internet-accessible.
- Check whether administrators recently viewed affected configuration pages.
- Track the linked GitHub issue for remediation details.
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-79: User-session and phishing behavior lookup
Client-side and session-facing weaknesses should be reviewed alongside initial-access and user-execution behaviors. 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-2021-36603 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:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
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:R/S:C/C:L/I:L/A:N2.82.7Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
6.1MediumVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/arendst/Tasmota/issues/12221CVE reference
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 Input During Web Page Generation ('Cross-site Scripting')
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.