CVE-2021-20240Network attack vector

Out-of-bounds write via wrapped GIF buffer length

Published May 28, 2021 · Updated Aug 3, 2024

Memory corruption in the GIF loader in GNOME GdkPixbuf before 2.42.0 allows remote attackers to crash applications with a crafted GIF. In gdk_pixbuf_gif_anim_iter_get_pixbuf(), the loader multiplies rowstride by image height without checking for gsize overflow, then passes the wrapped length to memset. User interaction or automated image ingestion is required; the out-of-bounds write causes a segmentation-fault crash and provides a path to code execution.

CVSS severity8.8
High
EPSS probability2.35%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Memory corruption in the GIF loader in GNOME GdkPixbuf before 2.42.0 allows remote attackers to crash applications with a crafted GIF. In gdk_pixbuf_gif_anim_iter_get_pixbuf(), the loader multiplies rowstride by image height without checking for gsize overflow, then passes the wrapped length to memset. User interaction or automated image ingestion is required; the out-of-bounds write causes a segmentation-fault crash and provides a path to code execution.

The record

CVE
CVE-2021-20240
Published
May 28, 2021
Updated
Aug 3, 2024
Vendor
GNOME
Product
GdkPixbuf
Classifications
CWE-191, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 28, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=gdk-pixbuf 2.42.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

GNOME · GdkPixbufversion=gdk-pixbuf 2.42.0

Published CVSS scores

8.3NIST NVDAV:N/AC:M/Au:N/C:P/I:P/A:C
8.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-191Integer Underflow (Wrap or Wraparound)
T1203Exploitation for Client Execution

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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