How severe is CVE-2019-5597?

CVE-2019-5597 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability high.

Is CVE-2019-5597 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 4% (88th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2019-5597?

CVE-2019-5597 primarily affects Freebsd. In total, 11 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2019-5597?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2019-5597 published?

CVE-2019-5597 was published on 2019-05-15 and last updated on 2026-06-17.

CVE-2019-5597

CVE-2019-5597 is a critical-severity vulnerability in Freebsd with a CVSS 3.x base score of 9.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-20.

Key facts

Severity: Critical (CVSS 3.x base score 9.1)
CVSS v2: 6.4
EPSS exploit prediction: 4% (88th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-20
Affected product: Freebsd
Published: 2019-05-15
Last modified: 2026-06-17

Description

In FreeBSD 11.3-PRERELEASE and 12.0-STABLE before r347591, 11.2-RELEASE before 11.2-RELEASE-p10, and 12.0-RELEASE before 12.0-RELEASE-p4, a bug in the pf IPv6 fragment reassembly logic incorrectly uses the last extension header offset from the last received packet instead of the first packet allowing maliciously crafted IPv6 packets to cause a crash or potentially bypass the packet filter.

Frequently asked questions

What is CVE-2019-5597?: In FreeBSD 11.3-PRERELEASE and 12.0-STABLE before r347591, 11.2-RELEASE before 11.2-RELEASE-p10, and 12.0-RELEASE before 12.0-RELEASE-p4, a bug in the pf IPv6 fragment reassembly logic incorrectly uses the last extension header offset from the last received packet instead of the first packet allowing maliciously crafted IPv6 packets to cause a crash or potentially bypass the packet filter.
How severe is CVE-2019-5597?: CVE-2019-5597 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability high.
Is CVE-2019-5597 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 4% (88th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2019-5597?: CVE-2019-5597 primarily affects Freebsd. In total, 11 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2019-5597?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2019-5597 published?: CVE-2019-5597 was published on 2019-05-15 and last updated on 2026-06-17.

References

Affected products (11)

cpe:2.3:o:freebsd:freebsd:11.2:-:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:11.2:p2:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:11.2:p3:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:11.2:p4:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:11.2:p5:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:11.2:p6:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:11.2:p7:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:11.2:p9:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:12.0:-:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:12.0:p1:*:*:*:*:*:*
cpe:2.3:o:freebsd:freebsd:12.0:p3:*:*:*:*:*:*

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