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HighVulnerabilityGHSA-494m-4556-wf5pupdated 30 Oct 2026, 22:57 UTC

imgproxy can crash when processing a specially crafted ICO image

A malformed ICO image file can make the imgproxy image service crash while processing it. Crashes can take the service offline for everyone who uses it.

Fixed in 4.0.17 · out Official source
SeverityHighCVSS 7.5 of 10
Being exploited?UnclearNo reports either way yet
Fix available?Yes4.0.17 · since 30 Oct 2026
How sure is this?Official sourceBacked by an official source

How the attack works simplified

  1. 1Crafted ICO fileEntry declares a tiny image data size
  2. 2imgproxy loads imageICO loader reads header fields past buffer
  3. 3Heap corruptedOut-of-bounds write alters next chunk size
  4. 4Worker abortsglibc detects invalid pointer on free
  5. ResultImage worker crashes, service disrupted

What happened

An out-of-bounds heap write in imgproxy's ICO loader (vips/icoload.c) corrupts heap memory when an ICO entry declares a very small image data size, causing the worker to abort (SIGABRT, Go panic, exit code 2).

Why it is dangerous: A crafted ICO file can repeatedly crash imgproxy workers, causing denial of service; the advisory describes deterministic worker aborts in observed production setups.

Are you affected?

You are affected if you run imgproxy v3.3.0 up to (not including) v4.0.17 and it processes ICO images, especially when local file sources are enabled (IMGPROXY_ENABLE_LOCAL_FILE).

Package / productAffected versionsFixed in
github.com/imgproxy/imgproxy/v3 · go>= 3.3.0, < 4.0.174.0.17

What to do

  1. Update imgproxy to version 4.0.17 or later
  2. If you cannot update right away, restrict or disable processing of ICO images and review whether IMGPROXY_ENABLE_LOCAL_FILE is needed
  3. Monitor imgproxy workers for unexpected crashes and restarts

Timeline

  1. 30 Oct 2026, 22:56 UTC
    Publicly disclosed
  2. 30 Oct 2026, 22:56 UTC
    Reported by GitHub Advisory · GitHub Advisory
  3. 30 Oct 2026, 22:57 UTC
    Picked up by Zero Radar

Sources 1 report, oldest first

Official vendor, government CERT or advisory database

Technical details

ID
GHSA-494m-4556-wf5p
CVSS
7.5 / 10
Disclosed
30 Oct 2026, 22:56 UTC
On Zero Radar
30 Oct 2026, 22:57 UTC (1 min after disclosure)
Last change
30 Oct 2026, 22:57 UTC

The plain-language parts and the attack diagram were written by an AI model (anthropic/claude-haiku-5.5) from the sources above. Facts like versions, exploitation and dates come from the sources themselves. How Zero Radar works

imgproxy can crash when processing a specially crafted ICO image · Zero Radar