CVE-2016-10166

Exploitation likely. EPSS gives it a 11% chance of exploitation in the next 30 days. A vendor fix is available.

CVSS 3.09.8Critical EPSS percentile96th11% chance in 30 days CISA KEVNot listedNo confirmed exploitation
No public exploit known FixVendor fixNo build named by the sources

Published 2017-03-15Updated 2026-05-13Sources: CVE.org, NVD, BDU

NVD CVE.org

What to do

The vendor has published a fix. Version details are below where the sources state them.

Steps

Written by AI from the record

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.

Vendor advisory Some work to apply

Check it yourselfA free OpenVAS check exists for this CVE. Run it against your hosts.Is your organisation exposed?Request an assessment to establish which checks fit your systems.

What it is

From the CVE record

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

Written by AI from the record

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.

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 you're affected

Application crashes
Possible server takeover
Image-processing disruption
Customer upload risk

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.

Exploitation

Where each signal puts this CVE on the scale from published to confirmed exploited.

EPSS96th

CISA KEV

Not in the catalog. CISA has not confirmed exploitation.

Public exploits

No public exploit or proof of concept found in the sources we track.

EPSS

11% chance of exploitation activity in the next 30 days, which ranks it in the 96th percentile of scored CVEs.

Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.

Attention now

Rising.

Real risk signals with little public attention so far.

Lifecycle

24 events over 3479 days, from the signal feeds we watch.

2026-09-23EPSS band change0 → moderateepss band change
2026-09-21EPSS band changemoderate → 0epss band change
2026-09-06EPSS band change0 → moderateepss band change
2026-09-05EPSS band changemoderate → 0epss band change
2026-08-31EPSS band change0 → moderateepss band change
2026-08-29EPSS band changemoderate → low

Affected products

libgdoss-projectaka gd graphics library
- libgdLibraryOSS Libraries / generic-library
Thomas Boutellindividual-dev · USaka libgd, cgic, gd library
- GD Graphics LibraryLibraryOSS Libraries / generic-library
Сообщество свободного программного обеспеченияoss-projectaka fsf
- libgd2LibraryOSS Libraries / generic-library

And 1 more affected product. See all after sign-in

Technical detail

CVSS 3.0 vector

Open in the CVSS calculator

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Scored 9.8 by NVD.

How it is reached

Attack Vector NetworkExploitable remotely over the network without any special conditions
Attack Complexity LowNo special conditions — the attack can be reliably reproduced
Privileges Required NoneNo authentication required — anyone can exploit this
User Interaction NoneNo user interaction needed — fully automated exploitation

Scope

Scope UnchangedImpact is limited to the vulnerable component itself

Impact if exploited

Confidentiality HighTotal information disclosure — all data in the component is compromised
Integrity HighTotal loss of integrity — attacker can modify any data in the component
Availability HighTotal denial of service — the component is completely unavailable