CVE-2021-21775Public exploitNetwork attack vector

Memory corruption via stale ImageLoader reference

Published Jul 7, 2021 · Updated Aug 3, 2024

Use-after-free in WebKitGTK before 2.32.3 allows remote attackers to disclose or corrupt process memory through a crafted webpage. ImageLoader::dispatchPendingErrorEvent retains a stale reference after an HTMLImageElement is freed, then accesses memory reallocated to a new Image object. A victim must open the page; Talos demonstrated a crash and reported that controlled heap reuse can expose data or cause further memory corruption.

CVSS severity6.8
Medium
EPSS probability1.26%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in WebKitGTK before 2.32.3 allows remote attackers to disclose or corrupt process memory through a crafted webpage. ImageLoader::dispatchPendingErrorEvent retains a stale reference after an HTMLImageElement is freed, then accesses memory reallocated to a new Image object. A victim must open the page; Talos demonstrated a crash and reported that controlled heap reuse can expose data or cause further memory corruption.

The record

CVE
CVE-2021-21775
Published
Jul 7, 2021
Updated
Aug 3, 2024
Vendor
WebKitGTK
Product
WebKitGTK
Classifications
CWE-416, T1203
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 7, 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=Webkit WebKitGTK 2.30.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

WebKitGTK · WebKitGTKversion=Webkit WebKitGTK 2.30.4

Published CVSS scores

6.8Cisco TalosCVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:L/A:L
8.0NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H
6.0NIST NVDAV:N/AC:M/Au:S/C:P/I:P/A:P

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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-416Use After Free
T1203Exploitation for Client Execution

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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