What’s Vulnerable › Vulnerabilities

CVE-2026-80733: net: remove WARN_ON_ONCE() from sk_mc_loop()

• Severity: unknown
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-03 · updated 2026-09-03

Description

In the Linux kernel, the following vulnerability has been resolved: net: remove WARN_ON_ONCE() from sk_mc_loop() sk_mc_loop() can be called for sockets that are neither AF_INET nor AF_INET6 (e.g. AF_PACKET sockets when sending packets via raw/packet socket over virtual devices such as VRF or ipvlan). In such cases, sk_family is not AF_INET/AF_INET6 and sk_mc_loop() falls through the switch statement and triggers WARN_ON_ONCE(1). Non-INET sockets do not support IP_MULTICAST_LOOP or IPV6_MULTICAST_LOOP options, so loopback should default to true without generating a warning.

Affected products

• Linux kernel: from 3.14.40 before 3.15; from 3.18.13 before 3.19; from 3.19.6 before 3.20; 4.0 — fixed in 3.15, 3.19, 3.20, 7.2

How to fix

Upgrade to a fixed version: Linux kernel 3.15, 3.19, 3.20, 7.2. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/0d75f2c1d0764efa756ad9c1e078d8c09ea8fc1f
• https://git.kernel.org/stable/c/97133c4d42654578fab95abe47359ebe784dde18
• https://git.kernel.org/stable/c/ad7dbb1d14b1b4406eca8ef9478e8de312ba0cfe
• https://git.kernel.org/stable/c/ad7fa2f411cb30f63d6725f111be134064cdb718
• https://git.kernel.org/stable/c/b8a39a09ae4eaae04309e1e38ed6a1101d967496
• https://git.kernel.org/stable/c/c8f256dc849205ccb2bd78bd99a3497b972b44e0
• https://git.kernel.org/stable/c/d2adc4e80b29e58b5162ae09f0f657a215806c8c
• https://git.kernel.org/stable/c/f625c742b33dc137c209dd13d1c5f12b1c18d71c

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