Security readout for executives and security teams
Plain-English summary
CVE-2021-40423 is a high-severity denial-of-service issue in a Reolink camera API component. A remote attacker could make the affected device unavailable, which matters if cameras support physical security monitoring, incident response, or site operations.
Executive priority
Prioritize remediation for internet-exposed or security-critical cameras first. The issue affects availability, not data theft, but outage of surveillance cameras can create operational and physical security blind spots.
Technical view
The vulnerability is in Reolink RLC-410W v3.0.0.136_20121102 cgiserver.cgi API command parsing. The CVE describes improper input handling leading to denial of service through crafted HTTP request sequences. CVSS 3.0 is 7.5, network exploitable, unauthenticated, availability impact only.
Likely exposure
Exposure is most likely where Reolink RLC-410W cameras running v3.0.0.136_20121102 are reachable from untrusted networks. The bundle does not prove other Reolink models or firmware versions are affected.
Exploitation context
The source bundle does not show CISA KEV listing or active exploitation evidence. Risk is still meaningful because the CVSS vector indicates remote, low-complexity, unauthenticated denial of service with no user interaction.
Researcher notes
Evidence is centered on the CVE record and Talos report. The affected product metadata in the bundle is incomplete, but the description names Reolink RLC-410W v3.0.0.136_20121102. No source-provided patch version or exploitation-in-the-wild evidence is included.
Mitigation direction
- Check Reolink and Talos guidance for firmware or vendor-specific remediation.
- Update affected cameras if a fixed vendor firmware is available.
- Restrict camera management/API access to trusted networks or VPN only.
- Remove direct internet exposure for affected camera interfaces.
- Monitor affected cameras for repeated outages or unexpected restarts.
Validation and detection
- Inventory Reolink RLC-410W devices and record firmware versions.
- Identify any device running v3.0.0.136_20121102.
- Confirm camera API or management interfaces are not internet reachable.
- Review network logs for unusual repeated HTTP access to camera APIs.
- Validate operational monitoring detects camera unavailability quickly.
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-20: Exact CWE lookup
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Open ATT&CK lookupCVE-2021-40423 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 (3.0)
- Known Exploited
- No
- Published
Vector: CVSS:3.0/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:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.0 score
7.5HighVector: CVSS:3.0/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://talosintelligence.com/vulnerability_reports/TALOS-2022-1432CVE reference · x_refsource_MISC
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.
Improper Input Validation
Improper Input Validation represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.