CVE-2023-41896
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Fake websocket server installation permits full takeover in Home Assistant Core
rank 27 = 0 + 23 + 0 + 4 + 0
rank@v1 · scheduled
Someone is already using it
CISA KEV catalog · public proof-of-concept · FIRST EPSS
EPSS 0.00271 · without this subject the record ranks 27
What it costs you if it fires
NVD CVSS base score, then the CNA's own
CVSS 9.0, from NVD · without this subject the record ranks 4
It is getting worse, not staying still
FIRST EPSS series, rescorings and bad loads removed
no persisting rise in 365 days · without this subject the record ranks 27
How much of the world it touches
NVD CPE configurations
2 products in the CPE ranges · without this subject the record ranks 23
Someone else already set the date
CISA KEV remediation due date
no CISA due date · without this subject the record ranks 27
$13,500 = $4.99M incident cost x 1 exposure x 0.00271 likelihood
udv@v1 · unaudited · wrong for you until you say what you run
$4.99M is the cost of a breach that happened, from IBM Cost of a Data Breach Report 2026, global average. It is not the value of any asset of yours. That average already covers breaches of every severity, so scaling it by exposure understates a partial-impact record. That is an assumption, not a measurement. Your own asset value goes in the decision record.
Hindsight · the state
Foresight · where to check next
This record is one instance of CWE-345, insufficient verification of data authenticity. The index holds 793 prior instances of this class, 2 KEV-listed. The nearest of its KEV-listed records are drawn beside this. taxonomy@v1
Sources disagree here.
Both shown, dated. We don't pick winners. disagreement-rules@v1
Running home-assistant core? Check your version
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Harm, if it fires from the vector and the weakness
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CISA KEV & Federal Remediation Deadline from the record and CISA
The fix, and how long it's been waiting.
Exploit Status & Known PoCs a ladder, not a score
Current rung: Nothing observed in held sources.
- RUNG 1Nothing observed in held sources
- RUNG 2Proof-of-concept published
- RUNG 3Exploited in the wild · CISA KEV listed
- RUNG 4Ransomware campaign use known
A rung lights from a row in the index, never from an assessment. "Held sources" is the true scope of the claim: this index reads the CVE record, NVD, CISA KEV, FIRST's EPSS and public proof-of-concept repositories, and it does not observe attacks.
Attack path
What it is stated by the CNA
Home assistant is an open source home automation. Whilst auditing the frontend code to identify hidden parameters, Cure53 detected `auth_callback=1`, which is leveraged by the WebSocket authentication logic in tandem with the `state` parameter. The state parameter contains the `hassUrl`, which is subsequently utilized to establish a WebSocket connection. This behavior permits an attacker to create a malicious Home Assistant link with a modified state parameter that forces the frontend to connect to an alternative WebSocket backend. Henceforth, the attacker can spoof any WebSocket responses and trigger cross site scripting (XSS). receipt
Read the rest of the CNA's description
Since the XSS is executed on the actual Home Assistant frontend domain, it can connect to the real Home Assistant backend, which essentially represents a comprehensive takeover scenario. Permitting the site to be iframed by other origins, as discussed in GHSA-935v-rmg9-44mw, renders this exploit substantially covert since a malicious website can obfuscate the compromise strategy in the background. However, even without this, the attacker can still send the `auth_callback` link directly to the victim user. To mitigate this issue, Cure53 advises modifying the WebSocket code’s authentication flow. An optimal implementation in this regard would not trust the `hassUrl` passed in by a GET parameter. Cure53 must stipulate the significant time required of the Cure53 consultants to identify an XSS vector, despite holding full control over the WebSocket responses. In many areas, data from the WebSocket was properly sanitized, which hinders post-exploitation. The audit team eventually detected the `js_url` for custom panels, though generally, the frontend exhibited reasonable security hardening. This issue has been addressed in Home Assistant Core version 2023.8.0 and in the npm package home-assistant-js-websocket in version 8.2.0. Users are advised to upgrade. There are no known workarounds for this vulnerability.
NVD's analysis a second authority
- severity
- 9 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H
- weakness
- CWE-345
- affected versions
- home-assistant < 2023.8.0; home-assistant-js-websocket < 8.2.0
- also scored by
- [email protected] 7.1 CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H
The CNA scored it 7.1 and NVD 9. Both are shown because both were published; we do not pick one.
check it yourself github.com github.com receipt
Movement the material steps
Show all 19 observations
19 observations held. A highlighted step crossed a promotion threshold. A step marked with a scoring model moved because the instrument was replaced, not because the vulnerability changed. receipt
The full biography
The record had been public for 2 years, 7 months when this index was last written.
The pattern, elsewhere
This record is one instance of CWE-345, insufficient verification of data authenticity. The index holds 793 prior instances of this class, 2 KEV-listed. The nearest of its KEV-listed records are drawn beside this. [email protected]
"Matches n of m" counts the attributes the two records can both be compared on: the CVSS metrics they share a version of, any weakness class beyond this one, and the vendor. fit-rules@v1
793 records in this class held. The six above are drawn from the ones CISA has listed as exploited, ranked by how much of the record matches this one. That is why every one of them is KEV-listed: the pool is, so the colour on those spokes says nothing the pool has not already said.
No curated product neighbourhood is held for this product, so the records above are the nearest this index can name. The neighbourhood table covers a small set of products and is extended by hand.
Siblings and hubs
Records related to this one
None. No alias set, and nothing in the corpus cites this identifier or shares its product family within 60 days.
Browse the index from here
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What usually comes next
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