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Fencer Intel
critical 9.1

CVE-2019-5597 json

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…

published 7y ago modified 4mo ago also EUVD-2019-15172

cvss
9.1
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
3.7%
EPSS 3.7% chance of exploitation in 30 days, percentile 89%
public exploits
0
none known

Summary

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.

Patch / fix

Is CVE-2019-5597 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Exploit prediction

3.66% chance of exploitation in the next 30 days, higher than 89% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • synacktiv.com https://www.synacktiv.com/ressources/Synacktiv_OpenBSD_PacketFilter_CVE-2019-5597_ipv6_frag.pdf referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.0 9.1 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
NVD 2.0 6.4 AV:N/AC:L/Au:N/C:N/I:P/A:P

Affected products

  • n/a FreeBSD

Classification

Weakness
  • CWE-20 Improper Input Validation

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.