CVE-2016-10166

Published: Mar 15, 2017Updated: May 13, 2026 Sources: CVE List NVD BDUCWE-191

9.8CRITICAL

NVD MITRE

Description

Integer underflow in the _gdContributionsAlloc function in gd_interpolation.c in the GD Graphics Library (aka libgd) before 2.2.4 allows remote attackers to have unspecified impact via vectors related to decrementing the u variable.

In plain language

AI Worth attention

libgd before 2.2.4 can be crashed or potentially taken over by a malicious image, so small businesses using it should arrange an update.

Executive summary

Remote, unauthenticated integer underflow in libgd image-smoothing memory allocation can process crafted input with an invalid allocation size, causing denial of service or potential code execution.

If affected, business impact

Application crashesPossible server takeoverImage-processing disruptionCustomer upload risk

What to do now

Check whether your servers or applications include libgd and identify its installed version.
Update libgd to version 2.2.4 or later through your operating system, application vendor, or deployment process.
If an update must wait, stop accepting untrusted images in affected image-smoothing workflows and restrict public access to the application.
Review application errors for image-processing crashes after applying the update.

Patch / advisory Some work to apply

What is it

This is a mistake in the image-processing library's size calculation when smoothing an image. It is like a warehouse system ordering a negative number of boxes, then mishandling the resulting inventory; a specially prepared image can make the application fail and may give an attacker control of it.

Who is affected

This matters to you if your website, application, or server uses libgd to process images, especially images supplied by customers or other outside sources. It is only a risk when an attacker can send crafted image data to a vulnerable application; no login or user action is required.

How urgent is it

Treat this as an amber-priority update because an attacker can trigger the flaw remotely with crafted image data. There is no record of active exploitation in CISA's catalog and no public exploit code on record, so schedule the update promptly in the current maintenance cycle.

What to do — in detail

Confirm exposure by inventorying deployed operating-system packages, containers, and application dependencies that include libgd, then determine whether untrusted image input can reach image-smoothing operations.

Target libgd 2.2.4 or later. Where libgd is supplied by an operating-system distribution or another application, use that supplier's updated package rather than replacing a bundled library independently.

Test the update with normal image-upload, resize, and smoothing jobs before production rollout, since applications that link against the library may need to be restarted or rebuilt after an update.

If patching is delayed, disable or isolate image-smoothing processing for untrusted uploads, block public upload endpoints where practical, and process required uploads in a restricted service. Review application and system logs for unexpected crashes or failures during image processing. CISA has not assigned a KEV remediation due date because this CVE is not listed in KEV.

Technical context

CVE-2016-10166 is rated CVSS 9.8 Critical (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H) and is CWE-191, an integer underflow. The network-reachable flaw is in _gdContributionsAlloc in gd_interpolation.c: crafted image data can cause a negative value to be used in memory allocation during image smoothing. Findings assess impact as application crash or potential arbitrary code execution. It is not in CISA KEV, and no public exploit code is recorded. EPSS predicts a 10.7% likelihood (96th percentile) with a flat trend; this is predictive, not evidence of exploitation.

This is a general assessment based on public vulnerability data. It does not account for your specific infrastructure — when in doubt, consult a security specialist.