Security Advisory 0034
Date: May 2nd, 2018
|1.0||May 2nd, 2018||Initial Release|
Affected Platforms: All EOS platforms
Affected Software Version: 4.20.1FX-Virtual-Router
The CVE-ID tracking this issue is CVE-2017-18017
CVSS v3: 9.8 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)
This advisory is to document a security vulnerability that affects Arista products.
The tcpmss_mangle_packet function in the Linux kernel allows potential remote attackers to crash the vEOS instance and possibly run arbitrary code when iptables rules with TCPMSS action are configured because of a use-after-free in tcpmss_mangle_packet. Arista’s vEOS router software is susceptible to this vulnerability.
BUG 212726 tracks this vulnerability. A fix for this issue will be available in a future release.
Note: This vulnerability can be exploited only when using Tunnelintf configuration, disabling this wherever possible can mitigate this attack.
Resolution: It is recommended to install the patch provided on affected versions of EOS
Patch file download URL:
Sha256 sum is:
[admin@switch flash]$ sha256sum SecurityAdvisory0034Hotfix.swix
- This hotfix can be installed on the affected version 4.20.1FX-Virtual-Router
- A reload of the switch is not required for the patch to take effect
- The configured tunnels may not work properly for up to 5 seconds while the patch is being applied.
Instructions to install the patch:
- Download the patch file and copy the file to the extension partition of the switch using one of the supported file transfer protocols:
switch#copy scp://10.10.0.1/SecurityAdvisory0034Hotfix.swix extension: switch#verify /sha256 extension:SecurityAdvisory0034Hotfix.swix
- Verify that the checksum value returned by the above command matches the provided SHA256 checksum for the file
- Install the patch using the extension command. The patch takes effect immediately at the time of installation.
- Verify that the patch is installed using the following commands:
switch#show extensions Name Version/Release Status Extension ------------------------------------ -------------------- ----------- --------- SecurityAdvisory0034Hotfix.swix 1.0.0/1.fc18 A, NI 1 awsha.rpm 0.1.1/1 A, I 1 awslogs.swix
- Make the patch persistent across reloads. This ensures that the patch is installed as part of the boot-sequence. The patch will not install on EOS versions with the security fix.
switch#copy installed-extensions boot-extensions switch#show boot-extensions SecurityAdvisory0034Hotfix.swix
For More Information:
If you require further assistance, or if you have any further questions regarding this security notice, please contact the Arista Networks Technical Assistance Center (TAC) by one of the following methods:
Open a Service Request:
By telephone: 408-547-5502