CVE-2019-15874Network attack vector

Remote kernel panic via stale mbuf access

Published Apr 28, 2020 · Updated Aug 5, 2024

Use-after-free in ipfw in FreeBSD 11.3 and 12.1 allows remote attackers to trigger a kernel panic via crafted TCP packets. When tcpoptions or tcpmss rules inspect a noncontiguous TCP header, ipfw's packet pull-up path can free an mbuf while later rule processing retains and dereferences stale packet pointers. Exposure requires ipfw rules using the tcpoptions or tcpmss keywords; successful exploitation interrupts the host by panicking its kernel.

CVSS severity9.8
Critical
EPSS probability1.35%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in ipfw in FreeBSD 11.3 and 12.1 allows remote attackers to trigger a kernel panic via crafted TCP packets. When tcpoptions or tcpmss rules inspect a noncontiguous TCP header, ipfw's packet pull-up path can free an mbuf while later rule processing retains and dereferences stale packet pointers. Exposure requires ipfw rules using the tcpoptions or tcpmss keywords; successful exploitation interrupts the host by panicking its kernel.

The record

CVE
CVE-2019-15874
Published
Apr 28, 2020
Updated
Aug 5, 2024
Vendor
The FreeBSD Project
Product
FreeBSD
Classifications
CWE-416, CWE-20, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 28, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=FreeBSD 12.1-STABLE before r356035, 12.1-RELEASE before 12.1-RELEASE-p4, 11.3-STABLE before r356036, 11.3-RELEASE before 11.3-RELEASE-p8

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The FreeBSD Project · FreeBSDversion=FreeBSD 12.1-STABLE before r356035, 12.1-RELEASE before 12.1-RELEASE-p4, 11.3-STABLE before r356036, 11.3-RELEASE before 11.3-RELEASE-p8

Published CVSS scores

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:P

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-416Use After Free
CWE-20Improper Input Validation
T1499Endpoint Denial of Service

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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