iOSOperating system · Cisco
CVE-2013-3436
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 · uneditedThe default configuration of the Group Encrypted Transport VPN (GET VPN) feature on Cisco IOS uses an improper mechanism for enabling Group Domain of Interpretation (GDOI) traffic flow, which allows remote attackers to bypass the encryption policy via certain uses of UDP port 848, aka Bug ID CSCui07698.
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 confidenceThe default configuration of Cisco IOS GET VPN enables Group Domain of Interpretation (GDOI) traffic flow via UDP port 848 using an improper mechanism that fails to properly enforce the encryption policy, allowing remote attackers to bypass intended encryption protections.
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
all versionsCVSS 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
- None
- Confidentiality
- Partial
- Integrity
- None
- Availability
- None
AV:N/AC:L/Au:N/C:P/I:N/A:N
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 checksWork through these to decide whether this CVE applies to you.
-
Identify if GET VPN is configuredRun 'show gdoi' or 'show crypto gdoi' to check if Group Domain of Interpretation (GET VPN) is enabled on the Cisco IOS deviceAffected if GDOI is configured and active - the device is using GET VPN with default settings
-
Verify GDOI UDP port 848 is in useRun 'show ip udp' or 'show crypto gdoi gm' to confirm GDOI is using UDP port 848 for Group Domain of InterpretationAffected if UDP port 848 is open and GDOI is actively using this port for communication
-
Check GDOI configuration for encryption policy enforcementRun 'show run | include gdoi' or 'show crypto gdoi ks' to examine the GDOI Key Server configuration - look for whether encryption policies are properly defined and enforcedAffected if The GDOI configuration shows default settings that fail to enforce encryption policy, allowing plaintext or unencrypted traffic flow
-
Inspect ACLs controlling GDOI trafficExamine the ACLs applied to GDOI with 'show crypto gdoi ks policy' - verify whether explicit permit/deny rules enforce encryption rather than allowing unencrypted UDP 848 trafficAffected if ACLs permit UDP 848 traffic without requiring encryption or without proper enforcement of the encryption policy
The environment is affected if GET VPN is enabled with default configuration that fails to enforce encryption policy on UDP port 848 GDOI traffic, allowing unencrypted or policy-violating traffic to bypass intended protections.
Generated from the published advisory. Verify against your own configuration.
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 dataReconfigure GET VPN to use proper GDOI traffic flow controls that enforce encryption policy rather than relying on the default insecure configuration; review and validate all UDP 848 traffic flows against the intended encryption policy.
Fix this in iOS
Scoped from the published advisory
- Consultation4.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,728.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2013-3436 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2013-3436 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
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.
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.
- 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