dbcve.org
Unified Computing SystemApplication · Cisco

CVE-2021-34736

HIGH · 7.5 CVSS v3.1 Published 2021-10-21
Fix available
A fix is available. Upgrade to 4.1 / 4.2 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
A vulnerability in the web-based management interface of Cisco Integrated Management Controller (IMC) Software could allow an unauthenticated, remote attacker to cause the web-based management interface to unexpectedly restart. The vulnerability is due to insufficient input validation on the web-based management interface. An attacker could exploit this vulnerability by sending a crafted HTTP request to an affected device. A successful exploit could allow the attacker to cause the interface to restart, resulting in a denial of service (DoS) condition.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A denial of service vulnerability exists in the web-based management interface of Cisco IMC Software. An unauthenticated remote attacker can exploit insufficient input validation by sending a crafted HTTP request, causing the web interface to unexpectedly restart and rendering the management interface unavailable.

MitigationApply the vendor-supplied patch or software update from Cisco for Cisco IMC Software. Until the patch is applied, monitor for interface availability and consider network-level access controls to limit exposure to unauthenticated HTTP requests.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Unified Computing SystemApplication
Affected:< 4.1\(2g\)>= 4.2, < 4.2\(1b\)< 4.1\(3e\)

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Locate Cisco IMC Software version
    Access the Cisco IMC web interface and navigate to the Admin or System Information page to view the software version, or use the CLI via SSH/console and run 'show version' or 'scope chassis' followed by 'show detail'
    Affected if The displayed version falls within the affected ranges: before 4.1(2g), from 4.2 up to before 4.2(1b), or before 4.1(3e)
  2. Confirm web-based management interface is enabled
    Log into Cisco IMC web interface and verify the Web UI service is active under Admin > Services or similar management section, or check via CLI with 'scope http' or 'show http'
    Affected if The web-based management interface is enabled and accessible on the network
  3. Verify network accessibility of IMC web interface
    Attempt to reach the IMC web interface via HTTP/HTTPS from a network location, or review firewall/access list configurations to confirm the management interface is exposed to network segments
    Affected if The IMC web interface port (HTTP port 80 or HTTPS port 443 by default) is reachable from network segments where untrusted users could send requests

You are affected if Cisco IMC Software version is before 4.1(2g), 4.2 up to before 4.2(1b), or before 4.1(3e), and the web-based management interface is enabled and network-accessible to unauthenticated users.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 4.1 / 4.2 or later
Fixed in 4.14.2
Interim mitigation

Apply the vendor-supplied patch or software update from Cisco for Cisco IMC Software. Until the patch is applied, monitor for interface availability and consider network-level access controls to limit exposure to unauthenticated HTTP requests.

Recommended fix High confidence

Cisco IMC 4.1(3e) or later for 4.1.x line; Cisco IMC 4.2(1b) or later for 4.2.x line

  1. 1. Identify the current version of Cisco IMC Software by accessing the web-based management interface or using CLI 'show version'
  2. 2. Navigate to the Cisco Software Download page at https://software.cisco.com/ and locate Cisco IMC Software for your hardware model
  3. 3. Download the fixed version: For 4.1.x line, download version 4.1(3e) or later; For 4.2.x line, download version 4.2(1b) or later
  4. 4. Upload the firmware image through the IMC web interface under Admin > Firmware Management > Firmware Update, or via CLI using 'scope firmware' and 'update boot-loader' commands
  5. 5. After installation, verify the new version by checking Admin > Firmware Management > Firmware Inventory or using 'show version' in CLI
  6. 6. Test that the web-based management interface responds normally to confirm DoS condition is resolved
Caveat Firmware updates may require brief downtime; ensure proper change management and backup procedures are followed before applying

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Unified Computing System Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,040
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,664.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2021-34736 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-34736 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data