CVE-2023-4809 pf incorrectly handles multiple IPv6 fragment headers
Attackers can bypass pf firewall rules by sending IPv6 packets with multiple fragment headers, allowing unauthorized traffic to reach the host.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2023-4809?
CVE-2023-4809 is a high-severity vulnerability in Freebsd Freebsd, published on 6 Sep 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-167
Which versions are affected by CVE-2023-4809?
It affects 1 product.
Products include Freebsd Freebsd.
How do I fix CVE-2023-4809?
No fix has been published for CVE-2023-4809 yet. Limit exposure of the affected software until one is available.
Is CVE-2023-4809 being exploited?
There is no known exploitation of CVE-2023-4809 in the wild and no public exploit code.
Other vulnerabilities in Freebsd Freebsd
Sources
Also known as GHSA-g6hh-x63c-83gf.