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iOSOperating system · Cisco

CVE-2015-0681

HIGH · 7.1 CVSS v2.0 Published 2015-07-24
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
80/100
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
The TFTP server in Cisco IOS 12.2(44)SQ1, 12.2(33)XN1, 12.4(25e)JAM1, 12.4(25e)JAO5m, 12.4(23)JY, 15.0(2)ED1, 15.0(2)EY3, 15.1(3)SVF4a, and 15.2(2)JB1 and IOS XE 2.5.x, 2.6.x, 3.1.xS, 3.2.xS, 3.3.xS, 3.4.xS, and 3.5.xS before 3.6.0S; 3.1.xSG, 3.2.xSG, and 3.3.xSG before 3.4.0SG; 3.2.xSE before 3.3.0SE; 3.2.xXO before 3.3.0XO; 3.2.xSQ; 3.3.xSQ; and 3.4.xSQ allows remote attackers to cause a denial of service (device hang or reload) via multiple requests that trigger improper memory management, aka Bug ID CSCts66733.

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

The TFTP server in Cisco IOS and IOS XE contains improper memory management that is triggered by multiple requests. Remote attackers can exploit this to cause a denial of service via device hang or reload. The vulnerability affects multiple IOS and IOS XE versions across several feature sets.

MitigationUpgrade to a fixed Cisco IOS or IOS XE version as specified in the Cisco advisory. If TFTP is not required, disable the TFTP server as a compensating control.

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\(33\)xn1= 12.2\(44\)sq1= 12.4\(23\)jy= 12.4\(25e\)jam1= 12.4\(25e\)jao5m= 15.0\(2\)ed1= 15.0\(2\)ey3= 15.1\(3\)svf4a= 15.2\(2\)jb1
Ios XeOperating system
Affected:= 2.5.0= 2.5.1= 2.5.2= 2.6.0= 2.6.1= 2.6.2= 3.1s.0= 3.1s.1= 3.1s.2= 3.1s.3= 3.1s.4= 3.1s.5

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
M
Authentication
None
Confidentiality
None
Integrity
None
Availability
Complete

AV:N/AC:M/Au:N/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. Verify TFTP server is enabled
    Execute 'show running-config | include tftp' or check configuration for 'tftp-server' entries under global config. On IOS, use 'show tftp' if available.
    Affected if TFTP server configuration exists and is active on the device. If TFTP is not configured/enabled, the device is not vulnerable to this flaw.
  2. Identify the IOS version
    Execute 'show version' and locate the 'IOS' or 'IOS-XE' version string in the output. Note the full version number including the train (e.g., 15.2(2)jb1).
    Affected if The displayed version matches any of these: 12.2(33)xn1, 12.2(44)sq1, 12.4(23)jy, 12.4(25e)jam1, 12.4(25e)jao5m, 15.0(2)ed1, 15.0(2)ey3, 15.1(3)svf4a, 15.2(2)jb1.
  3. Identify the IOS XE version
    Execute 'show version' and look for the 'IOS-XE' version string. Note the full version (e.g., 2.6.0, 3.1s.3).
    Affected if The displayed version matches any of these: 2.5.0, 2.5.1, 2.5.2, 2.6.0, 2.6.1, 2.6.2, 3.1s.0, 3.1s.1, 3.1s.2, 3.1s.3, 3.1s.4, 3.1s.5.
  4. Confirm TFTP server feature is in use
    Check if TFTP server is actively listening or servicing requests. Use 'show control-plane host open-ports' or verify TFTP configuration is applied to an interface.
    Affected if TFTP server is configured and actively running while the IOS/IOS XE version matches the affected versions list.

The device is vulnerable if TFTP server is enabled AND the running IOS or IOS XE version matches one of the specific versions listed in the affected products for this CVE.

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 to a fixed Cisco IOS or IOS XE version as specified in the Cisco advisory. If TFTP is not required, disable the TFTP server as a compensating control.

Fix this in iOS Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,130
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Scan for this in your stack

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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-2015-0681 in production — separate from our analysis above.

No notes yet

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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