CVE-2026-80901 ipvs: fix the checksum validations
Missing checksum validation in Linux kernel IPVS allows bypassing integrity checks for ICMPv6 packets, potentially enabling traffic manipulation.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-80901?
CVE-2026-80901 is a vulnerability in Linux, published on 4 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
ipvs: fix the checksum validations
ip_vs_in_icmp_v6() is missing checksum validation for ICMPv6 packets from clients. In fact, as for TCP/UDP we should validate the checksum for ICMP packets only when we mangle the packets on MASQ or on reply for tunnel.
Also, Sashiko points out that handle_response_icmp() being common for IPv4 and IPv6 is missing the pseudo-header calculation while validating ICMPv6 messages from real servers which is a problem if checksum is not validated by the hardware.
Fix the problems by creating ip_vs_checksum_common_check() helper and use it for TCP/UDP/ICMP both for IPv4 and IPv6. Rely on the nf_checksum() for validating the ICMP messages but use it also for TCP and UDP.
Use correct IP offset for IP_VS_DBG_RL_PKT for TCP/UDP/SCTP.
IPVS packets (TCP/UDP/SCTP/ICMP) do not need checksum validation on LOCAL_OUT (local clients or local real servers) and on FORWARD (traffic from servers on LAN). Do it only on LOCAL_IN, in case nf_checksum() is not called on PRE_ROUTING.
Also, ip_vs_checksum_complete() can be marked static.
Which versions are affected by CVE-2026-80901?
How do I fix CVE-2026-80901?
Apply the vendor's patch.
Is CVE-2026-80901 being exploited?
There is no known exploitation of CVE-2026-80901 in the wild and no public exploit code.
Sources
Also known as AZL-99662, BELL-CVE-2026-80901, DEBIAN-CVE-2026-80901, GHSA-mp45-vjm2-gvhg, UBUNTU-CVE-2026-80901.