Linux KernelOperating system · Linux
CVE-2013-4343
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 · uneditedUse-after-free vulnerability in drivers/net/tun.c in the Linux kernel through 3.11.1 allows local users to gain privileges by leveraging the CAP_NET_ADMIN capability and providing an invalid tuntap interface name in a TUNSETIFF ioctl call.
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 confidenceUse-after-free vulnerability in the Linux kernel's TUN/TAP driver (drivers/net/tun.c) allowing local users with CAP_NET_ADMIN capability to gain privileges by providing an invalid interface name in a TUNSETIFF ioctl call.
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
Linux KernelOperating system
>= 3.8, < 3.10.16>= 3.11, < 3.11.5
Ubuntu LinuxOperating system
= 13.04= 13.10CVSS 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
- Local
- Complexity
- M
- Authentication
- None
- Confidentiality
- Complete
- Integrity
- Complete
- Availability
- Complete
AV:L/AC:M/Au:N/C:C/I:C/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 checksWork through these to decide whether this CVE applies to you.
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Check kernel version against affected rangeRun `uname -r` or `cat /proc/version` to get the kernel version. Compare it to the affected ranges: >= 3.8, < 3.10.16 or >= 3.11, < 3.11.5Affected if Kernel version falls within either 3.8 to 3.10.15 or 3.11 to 3.11.4
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Verify TUN/TAP driver is availableCheck if the tun module is loaded with `lsmod | grep tun` or check for /dev/net/tun existence with `ls -la /dev/net/tun`Affected if The TUN/TAP driver module is loaded or /dev/net/tun exists (driver is available)
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Confirm CAP_NET_ADMIN capability exposureCheck if unprivileged users can access TUNSETIFF ioctl by examining if /dev/net/tun is world-writable or if specific users/groups have CAP_NET_ADMIN via `getcap -r /` or reviewing /etc/security/capability.conf if using Linux capabilitiesAffected if Non-privileged users have CAP_NET_ADMIN capability or can access /dev/net/tun without restrictions
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Verify TUN device permissionsRun `ls -la /dev/net/tun` and check the file permissions; also run `cat /proc/sys/kernel/tun` if available to check TUN configurationAffected if The TUN device is writable by the user in question or device permissions are overly permissive
The environment is affected if the kernel version is 3.8-3.10.15 or 3.11-3.11.4 AND the TUN/TAP driver is available AND the user in question has CAP_NET_ADMIN capability or can access /dev/net/tun.
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 data3.10.163.11.5
Apply kernel security patch or upgrade to a kernel version beyond 3.11.1 that contains the fix; ensure only trusted users have CAP_NET_ADMIN capability as a defense-in-depth measure.
Fix this in Linux Kernel
Scoped from the published advisory
- Consultation3.0 h
- Implementation4.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,880.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2013-4343 — 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-2013-4343 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
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
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