Security readout for executives and security teams
Plain-English summary
This flaw can let someone physically near the Wi-Fi network crash affected Cisco Aironet access points by abusing how they handle unexpected wireless frames. The business impact is service disruption, not data theft. Repeated reloads could make wireless connectivity unreliable for offices, campuses, or operational sites using vulnerable Aironet AP software.
Executive priority
Treat this as a high availability risk for sites relying on affected Cisco Aironet access points. It does not indicate data theft, but a nearby unauthenticated attacker could disrupt wireless service. Prioritize based on business dependence on Wi-Fi and the criticality of affected locations.
Technical view
CVE-2021-34740 is a WCP implementation error in Cisco Aironet AP software. Incorrect error handling for unexpected 802.11 frames can cause a packet buffer leak. Over time, buffer allocation failures can trigger an AP reload, producing denial of service. CVSS 3.1 is 7.4 with adjacent, unauthenticated attack requirements.
Likely exposure
Exposure is limited to Cisco Aironet access points running affected AP software and reachable over the wireless interface by an adjacent attacker. The source bundle does not provide exact affected version ranges, so inventory and vendor-advisory matching are required.
Exploitation context
The CVE is not listed as KEV in the provided bundle, and no cited source states active exploitation. Exploitation requires wireless adjacency and sending certain unexpected 802.11 frames; the reported impact is AP reload or denial of service, not confidentiality or integrity compromise.
Researcher notes
The public bundle identifies CWE-401, a packet buffer leak caused by incorrect WCP error handling for unexpected 802.11 frames. Version detail is incomplete in the bundle, so researchers should rely on Cisco’s advisory for affected and fixed release mapping before declaring exposure.
Mitigation direction
- Review Cisco’s advisory for affected releases, fixed software, and any listed workarounds.
- Inventory Cisco Aironet access points and map AP software versions against vendor guidance.
- Prioritize updates for APs supporting critical offices, campuses, or operational environments.
- Monitor wireless infrastructure for unexpected AP reloads or buffer allocation failure symptoms.
Validation and detection
- Confirm whether deployed access points run Cisco Aironet AP software.
- Check device versions against the Cisco advisory’s affected and fixed release information.
- Review AP logs and controller telemetry for unexplained reloads or recurring buffer allocation failures.
- Verify remediation by confirming updated software versions after maintenance.
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-401: 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-2021-34740 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
- 7.4 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/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:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H2.84Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.4HighVector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Source materials
- CVE List V5 sourceCVE List V5
- 20210922 Cisco Aironet Access Points WLAN Control Protocol Packet Buffer Leak Denial of Service VulnerabilityCVE reference · vendor-advisory, x_refsource_CISCO
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.
Missing Release of Memory after Effective Lifetime
Missing Release of Memory after Effective Lifetime represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.