CVE-2026-4748Network attack vector

Firewall policy bypass via incomplete rule hashing

Published Apr 1, 2026 · Updated Apr 1, 2026

Rule-processing error in affected FreeBSD pf releases allows remote attackers to bypass intended packet-filtering policy. The loader hashes address-range rules without including all range-defining factors, so distinct rules collide and every matching rule after the first is silently discarded as a duplicate. Exposure requires pf to load multiple rules that differ only in x.x.x.x - y.y.y.y ranges; discarded rules can cause overblocking or underblocking.

CVSS severity7.5
High
EPSS probability0.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Rule-processing error in affected FreeBSD pf releases allows remote attackers to bypass intended packet-filtering policy. The loader hashes address-range rules without including all range-defining factors, so distinct rules collide and every matching rule after the first is silently discarded as a duplicate. Exposure requires pf to load multiple rules that differ only in x.x.x.x - y.y.y.y ranges; discarded rules can cause overblocking or underblocking.

The record

CVE
CVE-2026-4748
Published
Apr 1, 2026
Updated
Apr 1, 2026
Vendor
The FreeBSD Project
Product
FreeBSD
Classifications
CWE-1023, CWE-754, CWE-480
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 1, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 1, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=14.3-RELEASE <p10
  2. Affected versionversion=14.4-RELEASE <p1
  3. Affected versionversion=15.0-RELEASE <p5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The FreeBSD Project · FreeBSDversion=14.3-RELEASE <p10; version=14.4-RELEASE <p1; version=15.0-RELEASE <p5

Published CVSS scores

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

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-1023Incomplete Comparison with Missing Factors
CWE-754Improper Check for Unusual or Exceptional Conditions
CWE-480Use of Incorrect Operator

Public exploit references

No public exploit references are available in this record.

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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