MQTTX through 1.13.3 Stored XSS via Topic Tree and JSON Tree Tooltips
- Exploited
- No known exploitation
- Fix
- No fix listed
- Who is exposed
- Not reported
- Published
- Last modified
- Whether it needs action now or is a reference record, by fixed rules, with why. Last checked is when cve.now last re-read it.What do these mean? →
- Reference
- Last checked
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 17/100 · provisional
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
MQTTX desktop, an MQTT client application, has a stored cross-site scripting flaw that lets an attacker run script in its Electron renderer, which has nodeIntegration enabled, by publishing malicious MQTT topic names or payloads. The attacker can do this remotely, without logging in, but the script runs only when a user hovers over Topic Tree or JSON tree nodes.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
Read the original description
MQTTX desktop through 1.13.3 contains a stored cross-site scripting vulnerability that allows attackers to inject script by publishing malicious MQTT topic names or payloads rendered unescaped in tooltips. Attackers controlling a broker or publishing to subscribed topics can execute script in the Electron renderer, which has nodeIntegration enabled, when victims hover Topic Tree or JSON tree nodes.
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure7/25Reachable over the network without a login · Unknown: No advisory context yet
- Reach?/20Unknown. No tracked technology or package matched
- Severity5.3/10CVSS 5.3
- No patch5/5No patch listed yet
What would change the score
- Would score about 72 if added to CISA KEV
- Would score about 67 if CISA's SSVC rates exploitation active
- Would score about 32 if advisories confirm default setups are exposed
Check your systems with an agent
Paste this into a coding or ops agent. It checks your systems read-only and reports a table per asset.
Check whether my systems are affected by CVE-2026-126495 (MQTTX through 1.13.3 Stored XSS via Topic Tree and JSON Tree Tooltips), using the cve.now data below. Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only. What cve.now has for CVE-2026-126495 (entry last updated 2026-11-11): Affected: - emqx MQTTX: through 1.13.3 Fixed versions: none listed yet. Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory. CISA KEV: CVE-2026-126495 is not listed as of cve.now's last read. This KEV status is for CVE-2026-126495 only. If you also check another CVE, look up its own KEV status; never assume it from this one. How to check: - Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory. Verify against the linked advisories before concluding, and cite the date you read each one: - https://github.com/emqx/MQTTX/issues/2180 - https://github.com/emqx/MQTTX/blob/v1.13.3/src/widgets/TreeView.vue#L195-L226 - https://github.com/emqx/MQTTX/blob/v1.13.3/src/widgets/JSONViewer.vue#L175-L184 - https://github.com/emqx/MQTTX/blob/v1.13.3/src/background.ts#L276-L283 - https://github.com/emqx/MQTTX - https://www.vulncheck.com/advisories/mqttx-through-1.13.3-stored-xss-via-topic-tree-and-json-tree-tooltips Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing. Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action. Entry: https://cve.now/CVE-2026-126495 For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example get_vulnerability with id CVE-2026-126495.
Timeline
- CVE published
- First seen by cve.now
Affected versions
- emqx MQTTX
through 1.13.3
Evidence 8
CVE record · 2
Establishes: The identifier and description.
- Record
- Record
Other links · 6
- Report
- Repository
- Repository
- Repository
- Repository
- Link
Corrections
None so far.
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Questions about CVE-2026-126495
Is CVE-2026-126495 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
Which versions are affected by CVE-2026-126495?
MQTTX: through 1.13.3.Source: cve.now feed data