CVE-2022-26531
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Multiple improper input validation flaws were identified in some CLI commands of Zyxel USG/ZyWALL series firmware versions 4.09 through 4.71, USG…
rank 31 = 1 + 20 + 0 + 10 + 0
rank@v1 · scheduled
Someone is already using it
CISA KEV catalog · public proof-of-concept · FIRST EPSS
EPSS 0.05673 · without this subject the record ranks 30
What it costs you if it fires
NVD CVSS base score, then the CNA's own
CVSS 7.8, from NVD · without this subject the record ranks 11
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 31
How much of the world it touches
NVD CPE configurations
20 products in the CPE ranges · without this subject the record ranks 21
Someone else already set the date
CISA KEV remediation due date
no CISA due date · without this subject the record ranks 31
$203,000 = $4.99M incident cost x 0.7179585840212677 exposure x 0.05673 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-20, improper input validation. The index holds 13347 prior instances of this class, 73 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 Zyxel USG/ZyWALL series firmware? 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
Affected & Fixed Versions as published
Show all 20 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
Multiple improper input validation flaws were identified in some CLI commands of Zyxel USG/ZyWALL series firmware versions 4.09 through 4.71, USG FLEX series firmware versions 4.50 through 5.21, ATP series firmware versions 4.32 through 5.21, VPN series firmware versions 4.30 through 5.21, NSG series firmware versions 1.00 through 1.33 Patch 4, NXC2500 firmware version 6.10(AAIG.3) and earlier versions, NAP203 firmware version 6.25(ABFA.7) and earlier versions, NWA50AX firmware version 6.25(ABYW.5) and earlier versions, WAC500 firmware version 6.30(ABVS.2) and earlier versions, and WAX510D firmware version 6.30(ABTF.2) and earlier versions, that could allow a local authenticated attacker to receipt
Read the rest of the CNA's description
cause a buffer overflow or a system crash via a crafted payload.
NVD's analysis a second authority
- severity
- 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- weakness
- CWE-20
- affected versions
- zyxel vpn100 firmware >= 4.30 <= 5.21; zyxel vpn1000 firmware >= 4.30 <= 5.21; zyxel vpn300 firmware >= 4.30 <= 5.21; and 17 more, listed in full below
- also scored by
- [email protected] 6.1 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H
The CNA scored it 6.1 and NVD 7.8. Both are shown because both were published; we do not pick one.
check it yourself zyxel.com seclists.org packetstormsecurity.com packetstormsecurity.com receipt
Movement the material steps
This score more than doubled inside 72 hours. Both observations are in the full history below.
Show all 20 observations
20 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
Exploit probability more than doubled between 2025-11-18 and 2025-11-21 (0.001 → 0.01558) and the record had been public for 4 years, 2 months when this index was last written.
The pattern, elsewhere
This record is one instance of CWE-20, improper input validation. The index holds 13347 prior instances of this class, 73 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
13347 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
These are index-wide views, not findings about CVE-2022-26531.
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.