Security readout for executives and security teams
Plain-English summary
CVE-2021-43612 is an availability risk in lldpd before 1.0.13. A malformed, short SONMP discovery packet can make the daemon read outside heap bounds while decoding traffic, potentially crashing the service. The disclosed impact is denial of service, not data theft or system takeover.
Executive priority
Prioritize patching where lldpd runs on production servers, network management hosts, or shared network segments. The main business risk is avoidable service disruption, not confirmed compromise. Treat as high priority for exposed infrastructure, but do not escalate as actively exploited based on current sources.
Technical view
The issue is in lldpd's sonmp_decode handling before version 1.0.13. Short SONMP packets can trigger an out-of-bounds heap read. The CVSS 3.1 vector is network, low complexity, no privileges, no user interaction, unchanged scope, and high availability impact.
Likely exposure
Exposure is most likely on systems running lldpd versions earlier than 1.0.13, including Linux distributions that shipped vulnerable packages. Risk is highest where lldpd processes discovery traffic from untrusted or loosely controlled network segments.
Exploitation context
The source bundle does not show CISA KEV listing or cited evidence of active exploitation. The vulnerability is remotely reachable over the network according to CVSS, but the documented impact is service disruption through malformed SONMP packet handling.
Researcher notes
The public record ties the flaw to lldpd SONMP decoding and an upstream fix in the 1.0.13 range. Available metadata lists CWE-787, although the description characterizes the behavior as an out-of-bounds heap read. No source bundle evidence confirms exploitation in the wild.
Mitigation direction
- Upgrade lldpd to version 1.0.13 or a vendor package containing the fix.
- Apply relevant distribution security updates, including Fedora advisories where applicable.
- Check vendor guidance before changing SONMP or lldpd protocol handling.
- Limit lldpd exposure on untrusted network segments where operationally feasible.
Validation and detection
- Inventory hosts and appliances running lldpd.
- Confirm installed lldpd versions are 1.0.13 or vendor-fixed builds.
- Review package changelogs or advisories for the CVE-2021-43612 fix.
- Identify network segments where lldpd receives discovery traffic.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-787: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2021-43612 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 7.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.5HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://lldpd.github.io/security.htmlCVE reference
- https://github.com/lldpd/lldpd/commit/73d42680fce8598324364dbb31b9bc3b8320adf7CVE reference
- https://github.com/lldpd/lldpd/compare/1.0.12...1.0.13CVE reference
- FEDORA-2023-88991d2713CVE reference · vendor-advisory
- FEDORA-2023-c0c184a019CVE reference · vendor-advisory
- FEDORA-2023-3e4feeadecCVE reference · vendor-advisory
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Out-of-bounds Write
Out-of-bounds Write represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.