CVE-2026-80901
Received Received - Intake

IPVS Missing Checksum Validation in Linux Kernel

Publication date: 2026-09-04

Last updated on: 2026-09-04

Assigner: kernel.org

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.

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Meta Information

Published
2026-09-04
Last Modified
2026-09-04
Generated
2026-09-05
AI Q&A
2026-09-04
EPSS Evaluated
N/A
NVD
CVE-2026-80901
EUVD
EUVD-2026-71651

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

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Exploitability

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KEV
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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel involves missing checksum validations for ICMPv6 packets in the IPVS (IP Virtual Server) subsystem. The issue affects how the kernel handles ICMPv6 packets from clients and servers, potentially allowing invalid or corrupted packets to bypass security checks. The fix introduces a helper function to standardize checksum validation for TCP/UDP/ICMP packets across IPv4 and IPv6.

Detection Guidance

This vulnerability involves missing checksum validation in IPVS for ICMPv6 packets and incorrect pseudo-header calculation in handle_response_icmp(). Detection requires kernel-level inspection. Check if your Linux kernel version includes the fix by running uname -a and comparing against patched versions. Monitor network traffic for ICMPv6 packets with invalid checksums using tools like tcpdump or Wireshark. Look for kernel logs indicating checksum validation issues.

Impact Analysis

This vulnerability could allow attackers to send malformed ICMPv6 packets that bypass network security checks, potentially leading to unauthorized access, data interception, or denial-of-service conditions. Systems using IPVS for load balancing or network address translation may be affected if checksum validation is not properly enforced.

Mitigation Strategies

Update the Linux kernel to the patched version that includes the fix for ipvs checksum validations. Monitor network traffic for ICMPv6 packets to ensure proper checksum handling.

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