CVE-2026-55996
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Unauthenticated Denial-of-Service via TLS SAN Stuffing in Rancher and cattle-cluster-agent
rank 11 = 0 + 11 + 0 + 0 + 0
rank@v1 · backlog
Someone is already using it
CISA KEV catalog · public proof-of-concept · FIRST EPSS
EPSS 0.00150 · without this subject the record ranks 11
What it costs you if it fires
NVD CVSS base score, then the CNA's own
CVSS 4.3, from the CNA · without this subject the record ranks 0
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 11
How much of the world it touches
NVD CPE configurations
0 products in the CPE ranges · without this subject the record ranks 11
Someone else already set the date
CISA KEV remediation due date
no CISA due date · without this subject the record ranks 11
$1,800 = $4.99M incident cost x 0.24048551839932833 exposure x 0.0015 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-770, allocation of resources without limits or throttling. The index holds 2390 prior instances of this class, 2 KEV-listed. taxonomy@v1
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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.
What it is stated by the CNA
A denial-of-service vulnerability was identified in multiple TLS listeners in Rancher. Both the cattle-cluster-agent component running in downstream clusters and the Rancher server itself use the dynamiclistener library to serve TLS traffic. Without an effective CN filter configured, dynamiclistener automatically appended to each serving certificate any hostname presented via Server Name Indication (SNI) in incoming TLS requests. An unauthenticated attacker with network access within the affected cluster could send a large number of TLS requests with distinct hostnames, causing the serving certificate to accumulate an unbounded number of Subject Alternative Names (SANs). receipt
Read the rest of the CNA's description
Eventually, the certificate grows large enough that TLS handshakes fail with an excessive message size error, causing a denial of service on the affected listeners.
NVD's analysis a second authority
- weakness
- CWE-770
- also scored by
- [email protected] 4.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
check it yourself github.com bugzilla.suse.com receipt
Movement
Only one observation of this value is held, so there is no movement to show yet.
The full biography
The pattern, elsewhere
This record is one instance of CWE-770, allocation of resources without limits or throttling. The index holds 2390 prior instances of this class, 2 KEV-listed. [email protected]
2390 records in this class held. The six above are ranked by exploit maturity, then recency.
Siblings and hubs
Records related to this one
No record cites this identifier and it carries no alias. Its defect family is below.
Its defect family
suse rancher
Of the 3 records in this family, this is the only one holding a stated fix version: 2.11.16; 2.12.12; 2.13.8; 2.14.4.
Grouped by shared product and weakness, not by shared vulnerability. Each record's own state is on its own page.
Family membership: held values
This record is one of a group, and the group's page describes all of them. This page is kept and dated, and the defect family's own page is the one we offer for indexing: the whole group.
Browse the index from here
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What usually comes next
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