CVE-2025-56233Public exploitNetwork attack vector

Connection interruption via in-window TCP RST or SYN

Published Sep 29, 2025 · Updated Sep 29, 2025

TCP denial of service in the OpenIndiana SunOS 5.11 kernel allows remote attackers to interrupt established connections with crafted packets. The TCP input path accepts an RST or SYN sequence number anywhere inside the current receive window instead of requiring the exact next expected value. An attacker who can send packets to an established flow can probe the sequence space in receive-window increments until one packet terminates the connection; no authentication or user interaction is required.

CVSS severity7.5
High
EPSS probability0.34%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

TCP denial of service in the OpenIndiana SunOS 5.11 kernel allows remote attackers to interrupt established connections with crafted packets. The TCP input path accepts an RST or SYN sequence number anywhere inside the current receive window instead of requiring the exact next expected value. An attacker who can send packets to an established flow can probe the sequence space in receive-window increments until one packet terminates the connection; no authentication or user interaction is required.

The record

CVE
CVE-2025-56233
Published
Sep 29, 2025
Updated
Sep 29, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-400, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 29, 2025CVE publishedPublication date reported by the CVE source.
  2. Sep 29, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
T1499.004Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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