Security readout for executives and security teams
Plain-English summary
Cisco Small Business Smart and Managed Switches may let an attacker reuse captured web management session credentials. If an administrator session is intercepted, the attacker could later access the same switch management interface with administrator privileges. The sources do not show CISA KEV listing or active exploitation.
Executive priority
Treat this as high priority for environments using affected Cisco small business switches, especially if management interfaces are broadly reachable. The main business risk is unauthorized administrative control of network infrastructure, but exploitation requires a captured valid session.
Technical view
CVE-2021-34739 is a CWE-613 session expiration flaw in Cisco Small Business Series switch web management. CVSS 3.1 score is 8.1 high, with network attack vector and high confidentiality, integrity, and availability impact. Exploitation requires a man-in-the-middle position to capture valid session credentials before replaying them.
Likely exposure
Exposure is most likely where Cisco Small Business Smart or Managed Switch web management is reachable from untrusted networks, shared networks, or paths where traffic interception is plausible. The provided bundle does not identify exact affected versions or CPEs.
Exploitation context
The cited description requires interception of a valid user session, then later replay against the same device. That raises attacker complexity compared with direct remote exploitation, but successful compromise could provide administrator-level management access. No provided source confirms active exploitation.
Researcher notes
Evidence supports a session credential replay issue caused by insufficient session expiration. The source bundle lacks affected version ranges, CPEs, patch names, and exploit-in-the-wild confirmation. Avoid assuming broader Cisco product impact beyond the listed Small Business Smart and Managed Switches.
Mitigation direction
- Identify Cisco Small Business Smart and Managed Switches in the environment.
- Check the Cisco advisory for affected releases, fixed software, and official workarounds.
- Restrict web management access to trusted administrative networks only.
- Disable external exposure of switch management interfaces where possible.
- Invalidate active sessions after remediation if the platform supports it.
- Monitor management logins and configuration changes for anomalies.
Validation and detection
- Inventory switch models and software versions against Cisco advisory guidance.
- Confirm management interfaces are not reachable from the internet.
- Review network paths where administrator sessions could be intercepted.
- Check logs for unexpected administrator access or configuration changes.
- Verify session handling after applying vendor-recommended updates.
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-613: 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-2021-34739 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
- 8.1 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/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:H/PR:N/UI:N/S:U/C:H/I:H/A:H2.25.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
8.1HighVector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- 20211103 Cisco Small Business Series Switches Session Credentials Replay 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.
Insufficient Session Expiration
Insufficient Session Expiration represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
