CVE-2009-0687: The pf_test_rule function in OpenBSD Packet Filter (PF), as used in OpenBSD 4.2 through 4.5, NetBSD 5.0 before

Q: How do I fix CVE-2009-0687?

midnightbsd: mitigate or apply the listed mitigation; miros: upgrade to newer than 10; netbsd: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Q: Is CVE-2009-0687 being exploited?

CVE-2009-0687 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2009-0687 affect?

CVE-2009-0687 affects midnightbsd, miros, netbsd. Severity is high (CVSS 7.8). The pf_test_rule function in OpenBSD Packet Filter (PF), as used in OpenBSD 4.2 through 4.5, NetBSD 5.0 before RC3, MirOS 10 and earlier, and MidnightBSD 0.3-current allows remote attackers to cause a denial of service (panic) via crafted I

Q: How urgent is CVE-2009-0687?

Priority 56/100. High severity; EPSS top 5%: very likely to be exploited; Public exploit reference

This week

HIGH 7.8MITIGATEUPGRADEMITIGATE

CVE-2009-0687 is a high-severity flaw (CVSS 7.8) affecting midnightbsd, miros, netbsd. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The pf_test_rule function in OpenBSD Packet Filter (PF), as used in OpenBSD 4.2 through 4.5, NetBSD 5.0 before RC3, MirOS 10 and earlier, and MidnightBSD 0.3-current allows remote attackers to cause a denial of service (panic) via crafted IP packets that trigger a NULL pointer dereference during translation, related to an IPv4 packet with an ICMPv6 payload.

Why this priority

High severity
EPSS top 5%: very likely to be exploited
Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	7.8 (High)
EPSS exploit chance	9.5% (top 5%)
CISA exploited list	No
Weakness	CWE-399
Published	2009-08-11
Last modified	2026-06-16

Publisher (CNA): CERT/CC · Vendor: midnightbsd · mirbsd · netbsd · openbsd

Last updated 2026-06-16 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2009-08-11 10:30 UTCPublished CVE record published
2026-06-16 23:05 UTCUpdated Record last modified

midnightbsd midnightbsd MITIGATE

Affected: 0.3-current

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.3-current

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

mirbsd miros UPGRADE

Affected: <= 10

Fixed in: newer than 10

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

netbsd netbsd MITIGATE

Affected: 5.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 5.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

openbsd openbsd MITIGATE

Affected: 4.2 · 4.3 · 4.4 · 4.5

Fixed in: no fixed release known

Safe to downgrade to: a release before 4.2

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Exploit-DB: Multiple Vendor - PF Null Pointer Dereference
Exploit-DB: OpenBSD 4.5 - IP datagram Null Pointer Deref Denial of Service
Exploit-DB: OpenBSD 4.5 - IP datagrams Remote Denial of Service

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2009-0687?

midnightbsd: mitigate or apply the listed mitigation; miros: upgrade to newer than 10; netbsd: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2009-0687 being exploited?

CVE-2009-0687 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2009-0687 affect?

CVE-2009-0687 affects midnightbsd, miros, netbsd. Severity is high (CVSS 7.8). The pf_test_rule function in OpenBSD Packet Filter (PF), as used in OpenBSD 4.2 through 4.5, NetBSD 5.0 before RC3, MirOS 10 and earlier, and MidnightBSD 0.3-current allows remote attackers to cause a denial of service (panic) via crafted I

How urgent is CVE-2009-0687?

Priority 56/100. High severity; EPSS top 5%: very likely to be exploited; Public exploit reference

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References

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