Security readout for executives and security teams
Plain-English summary
This flaw can let an unauthenticated remote attacker crash affected Cisco ASA or Firepower Threat Defense devices by sending a malicious HTTPS request. The business risk is outage: VPN, firewall, or security gateway functions may be interrupted while the device reloads.
Executive priority
Treat as high priority for exposed security gateways because exploitation can interrupt network access or perimeter security services. Prioritize externally reachable devices and operationally critical VPN or firewall infrastructure.
Technical view
CVE-2021-34704 affects the web services interface in Cisco ASA Software and Cisco FTD Software. The issue is improper input validation while parsing HTTPS requests, mapped to CWE-121 and CWE-787. CVSS 3.1 is 8.6, with network attack vector, low complexity, no privileges, no user interaction, and high availability impact.
Likely exposure
Exposure is most likely where Cisco ASA or FTD web services are reachable from untrusted networks. The supplied bundle does not identify exact vulnerable versions, configurations, or deployment modes; teams should confirm against Cisco’s advisory.
Exploitation context
The bundle supports remote unauthenticated denial of service via malicious HTTPS requests. It does not support claims of active exploitation; KEV status is false. No exploit maturity or public weaponization details are provided.
Researcher notes
The public bundle lacks exact affected version ranges and fixed-release details, so validation should pivot to Cisco’s advisory. Avoid assuming exploit availability or patch specifics beyond the cited vendor source.
Mitigation direction
- Review Cisco’s advisory for affected and fixed ASA/FTD releases.
- Upgrade affected devices according to Cisco’s official guidance.
- Restrict HTTPS web services exposure to trusted management paths where feasible.
- Prioritize internet-facing VPN or firewall edge devices first.
Validation and detection
- Inventory Cisco ASA and FTD devices and software versions.
- Check whether HTTPS web services are reachable from untrusted networks.
- Compare versions and configurations against Cisco’s advisory.
- Review device reload history for unexplained HTTPS-related DoS patterns.
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-121: 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 lookupCWE-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-2021-34704 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
- 8.6 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/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:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H3.94Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
8.6HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asafdt-webvpn-dos-KSqJAKPACVE 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.
Stack-based Buffer Overflow
Stack-based Buffer Overflow represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
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.