CVE-2026-46433

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.

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CVSS v3.1 Score

6.5

MEDIUM

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS — Exploit Prediction

0.0023

Probability of exploitation

0.13%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-125 Out-of-bounds Read

Affected Products

Vendor	Product	Versions
lldpd_project	lldpd	< 1.0.22

References

Advisories & Patches

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

Other References

https://github.com/lldpd/lldpd/releases/tag/1.0.22

Frequently Asked Questions

What is CVE-2026-46433? +

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. It has a CVSS v3.1 base score of 6.5 (MEDIUM).

How severe is CVE-2026-46433? +

CVE-2026-46433 has a CVSS v3.1 score of 6.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0023, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-46433? +

CVE-2026-46433 affects products from lldpd_project, specifically: lldpd. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-46433? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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