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Fencer Vulns
high 8.8

CVE-2021-30666 kev in the critical feed json

A buffer overflow issue was addressed with improved memory handling.

published 2021-09-08 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-17583

cvss
8.8
version 3.1, CNA
cisa kev
Exploited
added 2021-11-03
epss
3.0%
EPSS 3.0% chance of exploitation in 30 days, percentile 87%
public exploits
0
none known

Summary

A buffer overflow issue was addressed with improved memory handling. This issue is fixed in iOS 12.5.3. Processing maliciously crafted web content may lead to arbitrary code execution. Apple is aware of a report that this issue may have been actively exploited..

Patch / fix

cisa required action Apply updates per vendor instructions.

  • Apple iOS 12.5
  • wpewebkit Debian 14, Debian 13, Debian 12 2.26.3-1
  • webkit2gtk Debian 14, Debian 13, Debian 12 2.26.1-2

debian advisories DEBIAN-CVE-2021-30666

  • webkit2gtk Ubuntu 18.04 LTS 2.26.1-0ubuntu0.18.04.1

ubuntu advisories UBUNTU-CVE-2021-30666

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • LibRaw RHEL 8 0.19.5-2.el8
  • webkit2gtk3 RHEL 8 2.28.4-1.el8
  • webkit2gtk3-jsc RHEL 8 2.28.4-1.el8
  • gnome-settings-daemon RHEL 8 3.32.0-11.el8
  • webkitgtk4 RHEL 7 2.28.2-2.el7
  • webkitgtk4-jsc RHEL 7 2.28.2-2.el7
  • webkitgtk4 RHEL 7 ELS 2.48.3-2.el7_9
  • webkitgtk4-jsc RHEL 7 ELS 2.48.3-2.el7_9

red hat advisories RHSA-2025:10364RHSA-2020:4451RHSA-2020:4035

  • webkit2gtk3 SLES 15 SP2-BCL, SLE Real Time 15 SP2, SLE Module for Desktop Applications 15 SP3 +9 more 2.34.3-23.3
  • webkit2gtk3 SLES for SAP 15 SP1, SLES for SAP 15, SLES 15-LTSS +7 more 2.34.3-3.92.1
  • webkit2gtk3 SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES for SAP 12 SP3 +11 more 2.34.3-2.82.1

suse advisories SUSE-SU-2022:0182-2SUSE-SU-2022:0183-1SUSE-SU-2022:0182-1SUSE-SU-2022:0142-1

  • gtk3 openSUSE Tumbleweed 2.32.4-1.1
  • webkit2gtk3 openSUSE Leap 15.3 2.34.3-23.3

opensuse advisories openSUSE-SU-2024:11506-1openSUSE-SU-2022:0182-1

  • gvfs AlmaLinux 8 1.36.2-10.el8
  • vte291 AlmaLinux 8 0.52.4-2.el8
  • libsoup AlmaLinux 8 2.62.3-2.el8
  • potrace AlmaLinux 8 1.15-3.el8
  • tracker AlmaLinux 8 2.1.5-2.el8
  • nautilus AlmaLinux 8 3.28.1-14.el8
  • pipewire AlmaLinux 8 0.3.6-1.el8
  • PackageKit AlmaLinux 8 1.1.12-6.el8

almalinux advisories ALSA-2020:4451

  • gtk3 Rocky Linux 8 3.22.30-6.el8
  • LibRaw Rocky Linux 8 0.19.5-2.el8
  • vte291 Rocky Linux 8 0.52.4-2.el8
  • libsoup Rocky Linux 8 2.62.3-2.el8
  • potrace Rocky Linux 8 1.15-3.el8
  • tracker Rocky Linux 8 2.1.5-2.el8
  • pipewire Rocky Linux 8 0.3.6-1.el8
  • PackageKit Rocky Linux 8 1.1.12-6.el8

rocky linux advisories RLSA-2020:4451

  • webkit2gtk Alpine 3.20, Alpine 3.19, Alpine 3.18 +4 more 2.26.0-r0

alpine advisories ALPINE-CVE-2021-30666

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-30666 updated cvss 8.8

webkitgtk: Buffer overflow leading to arbitrary code execution

  • Red Hat Enterprise Linux 6 webkitgtk Red Hat Enterprise Linux 7 webkitgtk3, libwebkit2gtk
    affected: no fix available
  • Red Hat Enterprise Linux AppStream (v. 8) webkit2gtk3 2.28.4-1.el8, webkit2gtk3-jsc 2.28.4-1.el8
    fixed: vendor fix RHSA-2020:4451
  • Red Hat Enterprise Linux Client (v. 7) webkitgtk4 2.28.2-2.el7, webkitgtk4-jsc 2.28.2-2.el7 Red Hat Enterprise Linux Client Optional (v. 7) webkitgtk4 2.28.2-2.el7, webkitgtk4-jsc 2.28.2-2.el7 Red Hat Enterprise Linux ComputeNode (v. 7) webkitgtk4 2.28.2-2.el7, webkitgtk4-jsc 2.28.2-2.el7 Red Hat Enterprise Linux ComputeNode Optional (v. 7) webkitgtk4 2.28.2-2.el7, webkitgtk4-jsc 2.28.2-2.el7
    fixed: vendor fix RHSA-2020:4035
  • Red Hat Enterprise Linux Server (v. 7 ELS) webkitgtk4 2.48.3-2.el7_9, webkitgtk4-jsc 2.48.3-2.el7_9
    fixed: vendor fix RHSA-2025:10364
  • Red Hat Enterprise Linux Server (v. 7) webkitgtk4 2.28.2-2.el7, webkitgtk4-jsc 2.28.2-2.el7
    fixed: vendor fix RHSA-2020:4035
  • Red Hat Enterprise Linux Server Optional (v. 7 ELS) webkitgtk4 2.48.3-2.el7_9, webkitgtk4-jsc 2.48.3-2.el7_9
    fixed: vendor fix RHSA-2025:10364
  • Red Hat Enterprise Linux Server Optional (v. 7) webkitgtk4 2.28.2-2.el7, webkitgtk4-jsc 2.28.2-2.el7 Red Hat Enterprise Linux Workstation (v. 7) webkitgtk4 2.28.2-2.el7, webkitgtk4-jsc 2.28.2-2.el7 Red Hat Enterprise Linux Workstation Optional (v. 7) webkitgtk4 2.28.2-2.el7, webkitgtk4-jsc 2.28.2-2.el7
    fixed: vendor fix RHSA-2020:4035
  • Red Hat CodeReady Linux Builder (v. 8) gvfs 1.36.2-10.el8, LibRaw 0.19.5-2.el8, tracker 2.1.5-2.el8, vte291 0.52.4-2.el8, mutter 3.32.2-48.el8, gvfs-afc 1.36.2-10.el8, +22 more Red Hat Enterprise Linux 9 webkit2gtk3, webkit2gtk3-jsc Red Hat Enterprise Linux AppStream (v. 8) gdm 3.28.3-34.el8, gtk3 3.22.30-6.el8, gvfs 1.36.2-10.el8, potrace 1.15-3.el8, LibRaw 0.19.5-2.el8, tracker 2.1.5-2.el8, +74 more Red Hat Enterprise Linux BaseOS (v. 8) libsoup 2.62.3-2.el8, pygobject3 3.28.3-2.el8, python3-gobject 3.28.3-2.el8, python3-gobject-base 3.28.3-2.el8, gsettings-desktop-schemas 3.32.0-5.el8
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Timeline

  1. Published
  2. Added to CISA KEV
  3. CISA patch deadline
  4. CISA SSVC: exploitation active

Known exploited

Added
5 y ago
Patch by
2021-11-17 (4 y ago)
Ransomware
Not known
Required action
Apply updates per vendor instructions.
Vendor, product
Apple, iOS
CISA name
Apple iOS WebKit Buffer Overflow Vulnerability

CISA SSVC

Exploitation
Active, exploited in the wild
Automatable
no
Technical impact
total
Assessed
21 mo ago

Exploit prediction

2.97% chance of exploitation in the next 30 days, higher than 87% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
NVD 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
CNA 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
NVD 2.0 6.8 AV:N/AC:M/Au:N/C:P/I:P/A:P

Affected products

  • Apple iOS

Classification

Weakness
  • CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.