Bug 2487363 (CVE-2026-46433)

Summary: CVE-2026-46433 lldpd: lldpd: Denial of Service due to heap buffer over-read when processing VLAN-tagged Ethernet frames
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in lldpd, an implementation of IEEE 802.1ab (LLDP). A remote attacker on the adjacent network can send specially crafted Ethernet frames with 802.1Q VLAN (Virtual Local Area Network) tags. This can cause a 4-byte heap buffer over-read, leading to a denial of service (DoS) due to an application crash. This vulnerability occurs when the received frame size equals the interface Maximum Transmission Unit (MTU).
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Bug Depends On: 2488318, 2488321    
Bug Blocks:    

Description OSIDB Bzimport 2026-06-09 23:02:36 UTC 
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.