CVE-2023-4809
pf incorrectly handles multiple IPv6 fragment headers
- Published
- Updated
- Reserved
- Assigned by
- freebsd
Description
In pf packet processing with a 'scrub fragment reassemble' rule, a packet containing multiple IPv6 fragment headers would be reassembled, and then immediately processed. That is, a packet with multiple fragment extension headers would not be recognized as the correct ultimate payload. Instead a packet with multiple IPv6 fragment headers would unexpectedly be interpreted as a fragmented packet, rather than as whatever the real payload is. As a result, IPv6 fragments may bypass pf firewall rules written on the assumption all fragments have been reassembled and, as a result, be forwarded or processed by the host.
Timeline
ID reserved
By freebsd
Published
- 18 months later
· 18 months later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| NVDNVD · Modified | 3.1 | High7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N |
- EPSS (exploitation in 30 days)
- 0.80% · top 43% of all CVEs (7 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.5.
Weakness
Affected products
References (5)
- https://security.FreeBSD.org/advisories/FreeBSD-SA-23:10.pf.asc (opens in a new tab)vendor-advisoryx_transferred
- http://www.openwall.com/lists/oss-security/2023/09/08/5 (opens in a new tab)x_transferred
- http://www.openwall.com/lists/oss-security/2023/09/08/6 (opens in a new tab)x_transferred
- http://www.openwall.com/lists/oss-security/2023/09/08/7 (opens in a new tab)x_transferred
- https://security.netapp.com/advisory/ntap-20231221-0009/ (opens in a new tab)x_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2023-4809)Record last updated .