Understanding Libcurl Vulnerability Detection in Saner CVEM

Overview

Many users encounter confusion when Saner CVEM continues to report vulnerabilities related to libcurl, even after updating to the latest libcurl packages or manually deploying the libcurl.exe file on the endpoint. This article aims to clarify how Saner CVEM detects libcurl-related vulnerabilities, why simply pushing the latest libcurl.exe from the Patch Management may not resolve the detection, and what specific steps need to be followed to accurately remediate and close these findings. 

How Saner CVEM Detects Libcurl Vulnerabilities

Saner CVEM conducts a comprehensive file-system level scan to detect vulnerabilities associated with libcurl.dll. The detection process includes the following steps:

• Scanning the entire system particularly within directories like Program Files to locate all instances of libcurl.dll, as multiple applications (including Saner CVEM itself) may bundle this library.

  Note: This vulnerability is specifically associated with libcurl.dll, not libcurl.exe. Updating or replacing libcurl.exe alone will not resolve the detection unless the corresponding vulnerable DLL files are addressed.

• Extracting the version information embedded within each detected DLL.

• Validating each version against known vulnerable version ranges, as defined by associated CVEs.

If any instance of libcurl.dll is found to match a known vulnerable version regardless of whether newer versions exist elsewhere on the system the vulnerability will be flagged for the endpoint.

Why Saner CVEM Does Not Provide a Unified Patch Rather Vendor Link of Libcurl

Saner CVEM intentionally does not provide a direct patch for this vulnerability because:

• The libcurl vulnerability is not tied to a single application.

• Multiple applications on a system may use different versions of libcurl.dll.

• There is no standardized or guaranteed upgrade path to replace all vulnerable instances.

• Even after upgrading an application, the vendor may continue to bundle an outdated version of the DLL.

• Libcurl is a heavily shared dynamic library, and usage is vendor-specific. 

• Replacing shared DLLs across applications can break functionality if done with out knowledge of the current build dependability on that version of libcurl.dll.

Interpreting the Evidence View: Why You Might See Non-Vulnerable Applications Listed

A frequent source of confusion in libcurl vulnerability reports is the Evidence section in Saner CVEM. Users often report:

"Why does the Evidence view show applications with libcurl.dll that are already up to date or not even part of the vulnerable version range? The report is saying the device is vulnerable, but the version I see looks fine!"

Here’s why this happens — and why it’s not actually incorrect.

What Saner CVEM’s Evidence View Shows

The Evidence section provides a list of all detected instances of the target file in this case, libcurl.dll across the entire device, regardless of version.

Each entry in the Evidence view shows:

• The full file path to the libcurl.dll

• The version of that file

• The application context (if identifiable)

• Whether the version is within the vulnerable range or not

Why Non-Vulnerable Entries Appear

Saner CVEM intentionally displays both vulnerable and non-vulnerable instances in the Evidence view to provide full visibility. This serves two purposes:

1. Transparency: So security teams can review all known installations of the DLL, not just the problematic one.

2. Traceability: It helps in validating which version got upgraded and which copy remains outdated.

However, only the instances of Libcurl.dll that fall within the vulnerable version range actually trigger the vulnerability detection.

In short:

• Just because the Evidence tab shows multiple applications does not mean all of them are causing the vulnerability.

• The detection is triggered by even one vulnerable file — and the non-vulnerable ones are included for reference.

Example Scenario

Let’s say the CVE affects:

• libcurl.dll versions ≤ 7.83.1

SanerNow finds the following:

The Evidence tab will show all three entries, but the detection is caused only by the second and third rows.

What This Means for You

• If you see applications in the Evidence list that are not in the vulnerable range, you don’t need to take any action on those.

• Focus on the exact versions and paths that are listed as vulnerable.

• Remediation is complete only when all vulnerable instances are either removed or upgraded, regardless of how many non-vulnerable ones are present.

How to Identify and Remediate libcurl Vulnerabilities

Step 1: Locate All Detected Instances

Navigate to:

Device > [Select Device] > Vulnerabilities > Evidence

Look for entries showing:

• File path (e.g., C:\Program Files\AppX\libcurl.dll)

• Version (e.g., 7.83.1)

• Detected CVE and affected version range

Document all file paths where a vulnerable version is detected.

Step 2: Determine the Application Source

For each libcurl.dll instance:

• Identify which application installed or owns it.

• Cross-check the vendor’s advisory or documentation.

• Verify whether the DLL is part of an actively used application.

Step 3: Remediate the Vulnerability

Depending on the scenario:

a) Update the Parent Application

• If the DLL belongs to a known software product, update that product using the vendor's latest patch.

b) Replace Only the DLL (Advanced)

• Replace the vulnerable libcurl.dll manually with a safe version from the official cURL repository only if it does not break application functionality. Test thoroughly.

c) Remove Obsolete or Unused Software

• Uninstall outdated software that is no longer in use and still includes vulnerable libraries.

d) Exclude False Positives (with Caution)

• If you are confident that a detected instance is a custom or harmless build of libcurl.dll, you can use Saner CVEM’s exclusion feature to ignore that instance for future scans.

• Do not use this unless fully verified by your internal security/compliance team.