CVE-2021-30661

Home/CVE/Apple Multiple Products WebKit Storage Use-After-Free Vulnerability

CVE

Apple Multiple Products WebKit Storage Use-After-Free Vulnerability

A use after free issue was addressed with improved memory management. This issue is fixed in Safari 14.1, iOS 12.5.3, iOS 14.5 and iPadOS 14.5, watchOS 7.4, tvOS 14.5, macOS Big Sur 11.3. 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..

HIGH · CVSS 8.8 ⚠ CISA KEV EPSS 0.00027

Act now

Listed on CISA KEV (known exploited in the wild)
SSVC exploitation status: active
Public exploit or PoC is available
CVSS base score ≥ 7.0

Sigma rules8 YARA rules0

Look this up elsewhere - one-click external pivots

NVD CVE.org CISA Vulners Exploit-DB GitHub PoC VulnCheck KEV GreyNoise

▸ How to read a CVE - triage first, then detect and patch

This page is every public fact about CVE-2021-30661, cross-linked. Its job is to answer one question fast - does this need my attention now? - and then hand you the two things you do about it. Here is how an analyst reads it.

Triage: should I act now? Four signals, and they are not interchangeable:

CVSSseverity - how bad it is IF exploited, 0-10. A high CVSS alone is not urgency; a flaw can be a perfect 10 and never actually be attacked. EPSSprobability - a model’s estimate of the chance it is exploited in the next 30 days, 0-1. This is the “will it actually happen” signal. CISA KEVconfirmed - it is being exploited in the wild right now. The strongest signal on the page; KEV beats any score. Weaponisedavailability - public exploits / PoCs, and especially Metasploit modules rated Excellent / Great. Reliable, packaged exploit code means low-skill attackers can use it today.

How they combine: KEV, or a dependable Metasploit module, means patch now regardless of CVSS. High CVSS + low EPSS + no exploit is real but not an emergency - schedule it. Low CVSS but KEV-listed still gets patched now. The verdict above already weighed these for you; this is how it got there.

Then what - two workflows:

Detectwhen you cannot patch today, follow this CVE to the ATT&CK techniques it enables, then Build a SIEM detection (the green button) - author a rule, test it in Atomic, deploy it. That buys visibility while the patch waits. PatchAffected products / packages tell you if you are exposed; Fixed versions by distribution and Vendor advisories give the exact version that closes it.

Reading order for the panels below: verdict + badges, then Public exploits / Metasploit (is it weaponised), then ATT&CK techniques + Sigma / IDS rules (can I detect it), then Affected products / packages + Fixed versions (am I exposed, what patches it), then Threat actors / IOCs (who uses it), then Scoring & timeline / references (the evidence).

⬢

Required Remediation

Apply updates per vendor instructions.

View attack path from CVE-2021-30661

◆

ATT&CK techniques

Techniques this CVE enables - linked via CWECAPECATT&CK. High◆ = named directly in ATT&CK or Nuclei templates.

T1203 · Exploitation for Client Execution T1566 · Phishing

▤ Build a SIEM detection for these techniques

⬡

Weakness Classification

CWE-416Use After Free

▤

Affected Products & Versions

apple safari< 14.1
apple ipados< 14.5
apple iphone os< 12.5.3
apple iphone os>= 14.0 and < 14.5
apple macos>= 11.0 and < 11.3
apple tvos< 14.5
apple watchos< 7.4

▤

Affected Packages

Language-ecosystem packages (from OSV) tied to this CVE, with the version that fixes it - the dependency-level detail NVD doesn’t carry.

Ubuntu:18.04:LTS webkit2gtk fixed in 2.30.3-0ubuntu0.18.04.1

Ubuntu:20.04:LTS qtwebkit-opensource-src

Ubuntu:20.04:LTS webkit2gtk fixed in 2.30.3-0ubuntu0.20.04.1

Ubuntu:20.04:LTS wpewebkit

Ubuntu:22.04:LTS qtwebkit-opensource-src

Ubuntu:22.04:LTS wpewebkit

Ubuntu:24.04:LTS qtwebkit-opensource-src

Ubuntu:Pro:16.04:LTS qtwebkit-opensource-src

Ubuntu:Pro:16.04:LTS qtwebkit-source

Ubuntu:Pro:16.04:LTS webkit2gtk

Ubuntu:Pro:16.04:LTS webkitgtk

Ubuntu:Pro:18.04:LTS qtwebkit-opensource-src

Ubuntu:Pro:18.04:LTS qtwebkit-source

Ubuntu:Pro:18.04:LTS webkitgtk

⚠

Public Exploits & PoCs

These PoC and exploit links come from public sources and are not verified to be safe or functional. Review the code before running anything, and treat unverified entries as untrusted.

pocARPSyndicate/cvemon (trickest)

pocOstorlab/KEV (trickest)

pocOstorlab/known_exploited_vulnerbilities_detectors (trickest)

📦

Fixed versions by distribution

The package version that resolves this CVE on each Linux distribution, from the vendor’s published security data. fixed in shows a patched version exists; open means the package is listed as affected with no fix yet.
alpine v3.19webkit2gtk fixed in 2.30.0-r0
alpine v3.20webkit2gtk fixed in 2.30.0-r0
rhel 8gdm fixed in 1:3.28.3-39.el8
rhel 8glib2 fixed in 0:2.56.4-9.el8
rhel 8glib2-devel fixed in 0:2.56.4-9.el8
rhel 8glib2-fam open
rhel 8glib2-static open
rhel 8glib2-tests open
rhel 8webkit2gtk3 fixed in 0:2.30.4-1.el8
rhel 8webkit2gtk3-devel open
rhel 8webkit2gtk3-jsc fixed in 0:2.30.4-1.el8
rhel 8webkit2gtk3-jsc-devel open
suse sle15WebKitGTK-4.0-lang fixed in 0:2.48.1-150600.12.36.5
suse sle15WebKitGTK-4.1-lang fixed in 0:2.48.1-150600.12.36.5
suse sle15WebKitGTK-6.0-lang fixed in 0:2.48.1-150600.12.36.5
suse sle15libjavascriptcoregtk-4_0-18 fixed in 0:2.34.3-23.3
suse sle15libjavascriptcoregtk-4_1-0 fixed in 0:2.38.6-150400.4.39.1
suse sle15libjavascriptcoregtk-5_0-0 fixed in 0:2.36.0-150400.2.12
suse sle15libjavascriptcoregtk-6_0-1 fixed in 0:2.48.1-150600.12.36.5
suse sle15libwebkit2gtk-4_0-37 fixed in 0:2.34.3-23.3
suse sle15libwebkit2gtk-4_1-0 fixed in 0:2.48.1-150600.12.36.5
suse sle15libwebkit2gtk-5_0-0 fixed in 0:2.36.0-150400.2.12
suse sle15libwebkit2gtk3-lang fixed in 0:2.34.3-3.92.1
suse sle15libwebkitgtk-6_0-4 fixed in 0:2.48.1-150600.12.36.5
suse sle15typelib-1_0-JavaScriptCore-4_0 fixed in 0:2.34.3-3.92.1
suse sle15typelib-1_0-JavaScriptCore-4_1 fixed in 0:2.48.1-150600.12.36.5
suse sle15typelib-1_0-JavaScriptCore-5_0 fixed in 0:2.36.0-150400.2.12
suse sle15typelib-1_0-JavaScriptCore-6_0 fixed in 0:2.48.1-150600.12.36.5
suse sle15typelib-1_0-WebKit-6_0 fixed in 0:2.42.5-150600.10.36
suse sle15typelib-1_0-WebKit2-4_0 fixed in 0:2.34.3-23.3
suse sle15typelib-1_0-WebKit2-4_1 fixed in 0:2.36.0-150400.2.13
suse sle15typelib-1_0-WebKit2-5_0 fixed in 0:2.36.0-150400.2.12
suse sle15typelib-1_0-WebKit2WebExtension-4_0 fixed in 0:2.48.1-150600.12.36.5
suse sle15typelib-1_0-WebKit2WebExtension-4_1 fixed in 0:2.48.1-150600.12.36.5
suse sle15typelib-1_0-WebKitWebProcessExtension-6_0 fixed in 0:2.42.5-150600.10.36
suse sle15webkit2gtk-4_0-injected-bundles fixed in 0:2.34.3-23.3
suse sle15webkit2gtk-4_1-injected-bundles fixed in 0:2.42.5-150600.10.35
suse sle15webkit2gtk-5_0-injected-bundles fixed in 0:2.36.0-150400.2.12
suse sle15webkit2gtk3-devel fixed in 0:2.48.1-150600.12.36.5
suse sle15webkit2gtk3-soup2-devel fixed in 0:2.42.5-150600.10.35
suse sle15webkit2gtk4-devel fixed in 0:2.42.5-150600.10.36
suse sle15webkitgtk-6_0-injected-bundles fixed in 0:2.42.5-150600.10.36

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Sigma Hunt Rules

Exact rules name this CVE ID. Product rules name an affected product in their title. Related rules cover techniques used by actors who exploited this CVE. Showing the most relevant matches; the complete related set is on the full drill-down.

producthighSuspicious Microsoft Office Child Process - MacOS

producthighRemote Access Tool - Renamed MeshAgent Execution - MacOS

producthighBinary Padding - MacOS

productmediumSuspicious Execution via macOS Script Editor

productmediumSystem Information Discovery Via Sysctl - MacOS

productmediumNew File Exclusion Added To Time Machine Via Tmutil - MacOS

Show all 8 top matches

productmediumSuspicious MacOS Firmware Activity

productmediumDisk Image Mounting Via Hdiutil - MacOS

▣

Scoring & Timeline

8.8

HIGH · CVSS v3.1 · [email protected]

View on NVD

Attack Vector

Network Adjacent Local Physical

Attack Complexity

Low High

Privileges Required

None Low High

User Interaction

None Required

Scope

Unchanged Changed

Confidentiality

None Low High

Integrity

None Low High

Availability

None Low High

Published to NVD08 Sep 2021 · 03:15 PM

CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

SSVC triage · cisa-vulnrichment

Exploitation

active

Automatable

Technical impact

total

SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.

⚑

Vendor Advisories

rhsaRHSA-2025:10364Important
suse-csafopenSUSE-SU-2024:11506-1
suse-csafSUSE-SU-2022:0182-2
suse-csafopenSUSE-SU-2022:0182-1
suse-csafSUSE-SU-2022:0182-1
Show all 9 vendor advisoriessuse-csafSUSE-SU-2022:0183-1
suse-csafSUSE-SU-2022:0142-1
cisaKEV-CVE-2021-30661
rhsaRHSA-2021:1586Moderate

🔗

References & Sources

Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.

https://support.apple.com/en-us/HT212317Vendor Advisory

https://support.apple.com/en-us/HT212318Vendor Advisory

https://support.apple.com/en-us/HT212323Vendor Advisory

https://support.apple.com/en-us/HT212324Vendor Advisory

https://support.apple.com/en-us/HT212325Vendor Advisory

https://support.apple.com/en-us/HT212341Vendor Advisory

Show all 7 references

https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-30661Third Party AdvisoryUS Government Resource