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CVE-2026-89776: vxlan: vnifilter: enforce exact length of GROUP/GROUP6 attributes

• 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: 2026-09-16 · updated 2026-10-19

Description

In the Linux kernel, the following vulnerability has been resolved: vxlan: vnifilter: enforce exact length of GROUP/GROUP6 attributes The VXLAN VNI filter entry policy declares the GROUP/GROUP6 address attributes as NLA_BINARY with only a maximum length, so validate_nla() accepts a payload shorter than the address. The GROUP consumer reads it with nla_get_in_addr(), an unconditional 4-byte load, so a short attribute over-reads up to 3 bytes of uninitialised slab data, which are stored into remote_ip and echoed back via RTM_GETTUNNEL, disclosing kernel memory. Switch both entries to NLA_POLICY_EXACT_LEN() so the validator rejects any GROUP/GROUP6 that is not exactly 4 / 16 bytes; a valid address is always sent at full width.

Affected products

• Linux kernel: 5.18 — fixed in 7.3

How to fix

Upgrade to a fixed version: Linux kernel 7.3. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/47bfcc871576eaef6c8edab6749acd4b317306ea
• https://git.kernel.org/stable/c/984f831dda31b3a18f47454cf64989f65402879e
• https://git.kernel.org/stable/c/a9ec10815199f9879ba080241dc555efb1daf324
• https://git.kernel.org/stable/c/ad32e564c62ebf5ba76dd60a22af52c69d54d17b
• https://git.kernel.org/stable/c/daebc7064a1b4c12c98e52c4bceede7f2fcd573c
• https://git.kernel.org/stable/c/e12c4663529699f457b2988c1dfedf4d13b3b3be

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