dbcve.org
iOSOperating system · Cisco

CVE-2012-5036

MEDIUM · 6.8 CVSS v2.0 Published 2014-04-23
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
74/100
Remediation priority · Elevated
Remotely reachable 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
Cisco IOS before 12.2(50)SY1 allows remote authenticated users to cause a denial of service (memory consumption) via a sequence of VTY management sessions (aka exec sessions), aka Bug ID CSCtn43662.

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

Cisco IOS before version 12.2(50)SY1 contains a resource exhaustion vulnerability where authenticated remote users can cause memory consumption by creating a sequence of VTY (Virtual Terminal) exec management sessions. The device fails to properly release memory from terminated sessions, leading to eventual denial of service.

MitigationUpgrade Cisco IOS to version 12.2(50)SY1 or later. Additionally, implement VTY session limits and monitor for anomalous session creation patterns to detect exploitation attempts.

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
iOSOperating system
Affected:= 12.2\(33\)sxi4= 12.2\(33\)sxi5= 12.2\(33\)sxi6= 12.2\(33\)sxi7= 12.2\(33\)sxj= 12.2\(50\)sy

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
Authentication
Single
Confidentiality
None
Integrity
None
Availability
Complete

AV:N/AC:L/Au:S/C:N/I:N/A:C

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. Identify Cisco IOS version
    Execute 'show version' on the device CLI and locate the 'IOS' or 'Cisco IOS Software' version string in the output
    Affected if The version matches 12.2(33)sxi4, 12.2(33)sxi5, 12.2(33)sxi6, 12.2(33)sxi7, 12.2(33)sxj, or 12.2(50)sy exactly
  2. Verify VTY lines are configured
    Execute 'show running-config | include vty' or 'show line' to list configured VTY lines and their transport input settings
    Affected if VTY lines are configured and accessible (especially with transport input ssh or telnet allowing remote access)
  3. Review active and recent VTY sessions
    Execute 'show users' and 'show line' to list current active VTY sessions, their idle times, and session duration
    Affected if Multiple long-running or stale VTY sessions exist that should have terminated but remain in the session table
  4. Check system memory utilization
    Execute 'show memory summary' or 'show memory allocating-process table' to review available memory and identify potential memory depletion
    Affected if Free memory is significantly depleted or shows a pattern of gradual consumption that correlates with session activity
  5. Inspect session logging for anomalous patterns
    Review 'show logging' output and session audit logs for patterns such as rapid session creation from a single source, sessions not properly closing, or excessive exec processes
    Affected if Logs indicate session creation patterns inconsistent with normal administrative use, particularly sessions that terminate without proper cleanup

A user is affected if their Cisco IOS version matches one of the affected versions AND VTY lines are enabled and accessible, and they observe memory depletion or session cleanup failures corresponding to remote authenticated access.

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.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade Cisco IOS to version 12.2(50)SY1 or later. Additionally, implement VTY session limits and monitor for anomalous session creation patterns to detect exploitation attempts.

Fix this in iOS Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA1.0 h
10.0 hours of engineering $1,750
Get help mitigating

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,800.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2012-5036 — 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-2012-5036 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