What’s Vulnerable › Vulnerabilities

CVE-2026-46433: lldpd: Heap OOB Read in VLAN Decapsulation memmove

• Severity: medium (CVSS 6.5 v3.1)
• 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: 2026-06-09 · updated 2026-07-23
• Weakness: CWE-125

Description

lldpd is an implementation of IEEE 802.1ab (LLDP). Prior to version 1.0.22, lldpd_decode() in src/daemon/lldpd.c strips 802.1Q VLAN tags from received Ethernet frames by calling memmove() to shift the frame payload 4 bytes left. The third argument (byte count) is s - 2 * ETHER_ADDR_LEN but should be s - 2 * ETHER_ADDR_LEN - 4, causing a 4-byte heap buffer over-read past the malloc(h_mtu) allocation when the received frame size equals the interface MTU. This issue has been patched in version 1.0.22.

Affected products

• lldpd: before 1.0.22 — fixed in 1.0.22

How to fix

Upgrade to a fixed version: lldpd 1.0.22. Check the vendor advisory for mitigations.

References

• https://github.com/lldpd/lldpd/commit/ca931be63a9cae0fcd8e9b6ae4e916d49f141cd6
• https://github.com/lldpd/lldpd/pull/787
• https://github.com/lldpd/lldpd/releases/tag/1.0.22
• https://github.com/lldpd/lldpd/security/advisories/GHSA-2g8p-2h3j-63m3

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