NVD / CVE Program· CNA apple

CVE-2020-27918: A use after free issue was addressed with improved memory management.

HighCVSS 7.8 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 31/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 1.4% (FIRST EPSS); higher than 73.2% of all records.
Someone with local access to the system can trigger it. No account or password is required. A user must open a link or visit a page. No special conditions are required; it is repeatable.
Fixed version: accountsservice (AlmaLinux:8) 0.6.55-2.el8; accountsservice-devel (AlmaLinux:8) 0.6.55-2.el8; accountsservice-libs (AlmaLinux:8) 0.6.55-2.el8.

Low priority for now. Upgrade to accountsservice (AlmaLinux:8) 0.6.55-2.el8; accountsservice-devel (AlmaLinux:8) 0.6.55-2.el8; accountsservice-libs (AlmaLinux:8) 0.6.55-2.el8 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

A use after free issue was addressed with improved memory management. This issue is fixed in macOS Big Sur 11.0.1, watchOS 7.1, iOS 14.2 and iPadOS 14.2, iCloud for Windows 11.5, Safari 14.0.1, tvOS 14.2, iTunes 12.11 for Windows. Processing maliciously crafted web content may lead to arbitrary code execution.

Published: Dec 8, 2020
Updated: Jun 16, 2026
EPSS: 1.4% · 73th percentile
CWE: CWE-416

Report tools

JSON

Action score

Monitor

Low priority for now.

CVSS: 31 / 40 · 7.8 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 1.4%

Get told when this record changes

Not in KEV: no record of exploitation in the wild
No public exploit code on record
A fix has been released

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

Vendor	Product	CPE
apple	icloud	cpe:2.3:a:apple:icloud
apple	itunes	cpe:2.3:a:apple:itunes
apple	safari	cpe:2.3:a:apple:safari
apple	ipados	cpe:2.3:o:apple:ipados
apple	iphone os	cpe:2.3:o:apple:iphone_os
apple	macos	cpe:2.3:o:apple:macos
apple	tvos	cpe:2.3:o:apple:tvos
apple	watchos	cpe:2.3:o:apple:watchos
fedoraproject	fedora	cpe:2.3:o:fedoraproject:fedora
debian	debian linux	cpe:2.3:o:debian:debian_linux
webkitgtk	webkitgtk\+	cpe:2.3:a:webkitgtk:webkitgtk\+

Versions reported by the vendor

Affected version ranges reported by the assigning authority (apple). Independent of NVD's CPE analysis and usually ahead of it.

Apple iOS and iPadOS
- unspecified and later · before 14.2affected
Apple macOS
- unspecified and later · before 11.0affected
- unspecified and later · before 12.11affected
- unspecified and later · before 14.0affected
- unspecified and later · before 11.5affected
- unspecified and later · before 11.5affected
Apple tvOS
- unspecified and later · before 14.2affected
Apple watchOS
- unspecified and later · before 7.1affected

Affected versions · NVD (13)

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

apple icloudbefore 11.5
apple ipadosbefore 14.2
apple iphone osbefore 14.2
apple itunesbefore 12.11
apple macosbefore 11.0.1
apple safaribefore 14.0.1
apple tvosbefore 14.2
apple watchosbefore 7.1
debian debian linux10.0
fedoraproject fedora32
fedoraproject fedora33
fedoraproject fedora34
webkitgtk webkitgtk+before 2.30.6

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Ecosystem	Package	Affected range	Fix
AlmaLinux:8	accountsservice	before 0.6.55-2.el8	0.6.55-2.el8
AlmaLinux:8	accountsservice-devel	before 0.6.55-2.el8	0.6.55-2.el8
AlmaLinux:8	accountsservice-libs	before 0.6.55-2.el8	0.6.55-2.el8
AlmaLinux:8	gdm	before 1:40.0-15.el8	1:40.0-15.el8
AlmaLinux:8	gnome-autoar	before 0.2.3-2.el8	0.2.3-2.el8
AlmaLinux:8	gnome-calculator	before 3.28.2-2.el8	3.28.2-2.el8
AlmaLinux:8	gnome-classic-session	before 3.32.1-20.el8	3.32.1-20.el8
AlmaLinux:8	gnome-control-center	before 3.28.2-28.el8	3.28.2-28.el8
AlmaLinux:8	gnome-control-center-filesystem	before 3.28.2-28.el8	3.28.2-28.el8
AlmaLinux:8	gnome-online-accounts	before 3.28.2-3.el8	3.28.2-3.el8
AlmaLinux:8	gnome-online-accounts-devel	before 3.28.2-3.el8	3.28.2-3.el8
AlmaLinux:8	gnome-session	before 3.28.1-13.el8	3.28.1-13.el8
AlmaLinux:8	gnome-session-kiosk-session	before 3.28.1-13.el8	3.28.1-13.el8
AlmaLinux:8	gnome-session-wayland-session	before 3.28.1-13.el8	3.28.1-13.el8
AlmaLinux:8	gnome-session-xsession	before 3.28.1-13.el8	3.28.1-13.el8
AlmaLinux:8	gnome-settings-daemon	before 3.32.0-16.el8.alma	3.32.0-16.el8.alma
AlmaLinux:8	gnome-shell	before 3.32.2-40.el8	3.32.2-40.el8
AlmaLinux:8	gnome-shell-extension-apps-menu	before 3.32.1-20.el8	3.32.1-20.el8
AlmaLinux:8	gnome-shell-extension-auto-move-windows	before 3.32.1-20.el8	3.32.1-20.el8
AlmaLinux:8	gnome-shell-extension-common	before 3.32.1-20.el8	3.32.1-20.el8
AlmaLinux:8	gnome-shell-extension-dash-to-dock	before 3.32.1-20.el8	3.32.1-20.el8
AlmaLinux:8	gnome-shell-extension-desktop-icons	before 3.32.1-20.el8	3.32.1-20.el8
AlmaLinux:8	gnome-shell-extension-disable-screenshield	before 3.32.1-20.el8	3.32.1-20.el8
AlmaLinux:8	gnome-shell-extension-drive-menu	before 3.32.1-20.el8	3.32.1-20.el8

+85

Same product

apple: all records

Other highest-scoring records for the same primary product.

CVE-2019-8506A type confusion issue was addressed with improved memory handling.KEV
70This week
CVE-2020-27932A type confusion issue was addressed with improved state handling.KEV
64This week
CVE-2020-9850A logic issue was addressed with improved restrictions.
62This week

Published before and after this one in the same product

← EarlierCVE-2020-27912Dec 8, 2020 · An out-of-bounds write was addressed with improved input validation.
32Monitor
← EarlierCVE-2020-27917Dec 8, 2020 · A use after free issue was addressed with improved memory management.
32Monitor
Later →CVE-2020-9991Dec 8, 2020 · This issue was addressed with improved checks.
31Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / package	Fixed version	Source
almalinux:accountsservice	0.6.55-2.el8 · AlmaLinux:8	Package registry (OSV)
almalinux:accountsservice-devel	0.6.55-2.el8 · AlmaLinux:8	Package registry (OSV)
almalinux:accountsservice-libs	0.6.55-2.el8 · AlmaLinux:8	Package registry (OSV)
almalinux:gdm	1:40.0-15.el8 · AlmaLinux:8	Package registry (OSV)
almalinux:gnome-autoar	0.2.3-2.el8 · AlmaLinux:8	Package registry (OSV)
almalinux:gnome-calculator	3.28.2-2.el8 · AlmaLinux:8	Package registry (OSV)
almalinux:gnome-classic-session	3.32.1-20.el8 · AlmaLinux:8	Package registry (OSV)
almalinux:gnome-control-center	3.28.2-28.el8 · AlmaLinux:8	Package registry (OSV)
almalinux:gnome-control-center-filesystem	3.28.2-28.el8 · AlmaLinux:8	Package registry (OSV)
almalinux:gnome-online-accounts	3.28.2-3.el8 · AlmaLinux:8	Package registry (OSV)
almalinux:LibRaw	0.19.5-3.el8 · AlmaLinux:8	Package registry (OSV)
almalinux:LibRaw-devel	0.19.5-3.el8 · AlmaLinux:8	Package registry (OSV)
alpine:webkit2gtk	2.30.6-r0 · Alpine:v3.13	Package registry (OSV)
debian:webkit2gtk	2.30.6-1 · Debian:12	Package registry (OSV)
debian:wpewebkit	2.30.6-1 · Debian:12	Package registry (OSV)
opensuse:webkit2gtk3	2.32.0-lp152.2.13.1 · openSUSE:Leap 15.2	Package registry (OSV)
red hat:LibRaw	0:0.19.5-3.el8 · Red Hat:enterprise_linux:8::appstream	Package registry (OSV)
red hat:LibRaw-debuginfo	0:0.19.5-3.el8 · Red Hat:enterprise_linux:8::appstream	Package registry (OSV)
red hat:LibRaw-debugsource	0:0.19.5-3.el8 · Red Hat:enterprise_linux:8::appstream	Package registry (OSV)
red hat:webkit2gtk3	0:2.32.3-2.el8 · Red Hat:enterprise_linux:8::appstream	Package registry (OSV)
red hat:webkit2gtk3-debuginfo	0:2.32.3-2.el8 · Red Hat:enterprise_linux:8::appstream	Package registry (OSV)
red hat:webkit2gtk3-debugsource	0:2.32.3-2.el8 · Red Hat:enterprise_linux:8::appstream	Package registry (OSV)
red hat:webkit2gtk3-devel	0:2.32.3-2.el8 · Red Hat:enterprise_linux:8::appstream	Package registry (OSV)
red hat:webkit2gtk3-devel-debuginfo	0:2.32.3-2.el8 · Red Hat:enterprise_linux:8::appstream	Package registry (OSV)
red hat:webkit2gtk3-jsc	0:2.32.3-2.el8 · Red Hat:enterprise_linux:8::appstream	Package registry (OSV)
red hat:webkit2gtk3-jsc-debuginfo	0:2.32.3-2.el8 · Red Hat:enterprise_linux:8::appstream	Package registry (OSV)
red hat:webkit2gtk3-jsc-devel	0:2.32.3-2.el8 · Red Hat:enterprise_linux:8::appstream	Package registry (OSV)
red hat:webkit2gtk3-jsc-devel-debuginfo	0:2.32.3-2.el8 · Red Hat:enterprise_linux:8::appstream	Package registry (OSV)
rocky linux:accountsservice	0:0.6.55-2.el8 · Rocky Linux:8	Package registry (OSV)
rocky linux:gdm	1:40.0-15.el8 · Rocky Linux:8	Package registry (OSV)

+11

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · variant or chain candidate · public bounty program.

Technical details

Attack conditions

Someone with local access to the system can trigger it.
No account or password is required.
A user must open a link or visit a page.
No special conditions are required; it is repeatable.

If successful

Confidentiality: high · data can be read
Integrity: high · data or configuration can be modified
Availability: high · the service can be disrupted

Attack vector: Local
Attack complexity: Low
Privileges required: None
User interaction: Required
Scope: Unchanged
Confidentiality impact: High
Integrity impact: High
Availability impact: High

Weakness class (CWE)

CWE-416 · Use After Free

CVSS vector

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

nvd-primary

Root cause

After a memory region is freed, another reference pointing to it is still used. By then, the same region may have been allocated for different data.

The bug in code

The whole CWE-416 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1free(dev->buf);
2/* ... another thread is still running ... */
3process(dev->buf);

Fixed

1lock(&dev->lock);
2free(dev->buf);
3dev->buf = NULL;
4unlock(&dev->lock);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log (1)

Fix✗ → ✓Sep 28, 2026, 10:45 PM UTC

For records you follow, these changes also arrive as notifications. →

References

seclists.org/fulldisclosure/2020/Dec/32

Show all references (13 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records