CVE-2021-21004
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Cross-site Scripting Vulnerability in Phoenix Contact FL SWITCH SMCS series products
rank 24 = 0 + 15 + 0 + 9 + 0
rank@v1 · backlog
Someone is already using it
CISA KEV catalog · public proof-of-concept · FIRST EPSS
EPSS 0.00581 · without this subject the record ranks 24
What it costs you if it fires
NVD CVSS base score, then the CNA's own
CVSS 6.1, from NVD · without this subject the record ranks 9
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 24
How much of the world it touches
NVD CPE configurations
15 products in the CPE ranges · without this subject the record ranks 15
Someone else already set the date
CISA KEV remediation due date
no CISA due date · without this subject the record ranks 24
$20,800 = $4.99M incident cost x 0.7179585840212677 exposure x 0.00581 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-79, improper neutralization of input during web page generation ('cross-site scripting'). The index holds 47894 prior instances of this class, 32 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 Phoenix Contact FL SWITCH? Check your version
A deterministic range check against the ranges this record publishes. It tells you where a version sits in the record, not whether your deployment is exploitable. No account needed.
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Harm, if it fires from the vector and the weakness
Written for the ticket you're about to file.
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
Affected & Fixed Versions as published
Show all 15 published ranges
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
In Phoenix Contact FL SWITCH SMCS series products in multiple versions an attacker may insert malicious code via LLDP frames into the web-based management which could then be executed by the client. receipt
NVD's analysis a second authority
- severity
- 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
- weakness
- CWE-79
- affected versions
- phoenixcontact fl switch smcs 16tx firmware <= 4.70; phoenixcontact fl switch smcs 14tx\/2fx firmware <= 4.70; phoenixcontact fl switch smcs 14tx\/2fx-sm firmware <= 4.70; and 12 more, listed in full below
- also scored by
- [email protected] 7.4 CVSS:3.1/AV:A/AC:L/PR:N/UI:R/S:C/C:L/I:H/A:N
The CNA scored it 7.4 and NVD 6.1. Both are shown because both were published; we do not pick one.
check it yourself cert.vde.com receipt
Movement the material steps
Show all 13 observations
13 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 4 years, 11 months when this index was last written.
The pattern, elsewhere
This record is one instance of CWE-79, improper neutralization of input during web page generation ('cross-site scripting'). The index holds 47894 prior instances of this class, 32 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
47894 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
No record cites this identifier and it carries no alias. The advisory that covers it is below.
Fixed with these, by one advisory
vde-2021-023
Of the 3 records in this advisory that state one, this holds the lowest EPSS percentile: 0.45499.
Listed because one advisory covers them, not because they are the same defect. Each record's own state is on its own page.
Grouping: held values
Browse the index from here
These are index-wide views, not findings about CVE-2021-21004.
What usually comes next
Everything above needs no account. What is below is work: assembling it, scoping it to your estate, watching it, and handing it to someone else.