Patching the Heap-Based Buffer Overflow (CVE-2019-16928) vulnerability in Exim email server software



    After the recent discovery of the remote code execution in Exim servers, another vulnerability has to come to light in the popular, open-source Mail Transer Agent at the end of the month. The maintainence team for Exim has released a critical security update to fix a heap-based buffer overflow vulnerability in string_vformat in the string.c file, without which, the vulnerable system could fall prey to remote code execution attacks.

    CVE assigned:


    Affected Software's:

    Exim server versions ranging from 4.92 through 4.92.2


    To address this vulnerability, the vendor has released patches for Exim package in all the platforms affected. For more information, please refer to our blog:

    Use SanerNow platform to apply this critical patch quickly across the organization as shown below.


    Vulnerability detection and patching of Exim:

    1. Login to SanerNow platform
    2. Switch to the account/site specific view and Go to 'VM tool'
    3. If your Application (Exim) is vulnerable, Saner lists CVE-2019-16928 in 'Top Vulnerabilities or 'Recently Discovered Vulnerabilities as shown in the below image:


    1. Search for this vulnerability in VM tool. If you are affected, apply the patch through PM -> Missing Patches.
    2. Select 'Groups/Devices in the 'Asset Source' section and click 'Apply'.
    3. Select the product 'Exim' from the 'Asset' section as shown in the below image:


    1. Select ‘Apply Selected Patches’ at the rightmost corner. This will prompt for ‘Creating Patch Task’. Fill in ‘Task Name’ and ‘Remediation Schedule as per your preference and click on ‘Apply Selected Patches as shown below:


    Remediation job will be created, which will fix the vulnerability by upgrading Exim to the latest patch version.

    1. Once remediation is done, the Saner agent automatically scans again and uploads the result to SanerNow as shown below:


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