Secuno
ENNL
Book demo

CVE-2021-30858

Apple iOS, iPadOS, macOS Use-After-Free

8.8 HIGHActively exploited (CISA KEV)EPSS 13.4%
  1. Published24 Aug 2021
  2. Added to CISA KEV3 Nov 2021
  3. Remediation due17 Nov 2021
Actively exploited (CISA KEV)

Apple iOS, iPadOS, and macOS WebKit contain a use-after-free vulnerability that leads to code execution when processing maliciously crafted web content. This vulnerability could impact HTML parsers that use WebKit, including but not limited to Apple Safari and non-Apple products which rely on WebKit for HTML processing.

Added to KEV: 3 Nov 2021Federal remediation due: 17 Nov 2021

Description

A use after free issue was addressed with improved memory management. This issue is fixed in iOS 14.8 and iPadOS 14.8, macOS Big Sur 11.6. 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.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionRequired
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Affected products

Apple iPadOS≥ 13.1 < 14.8
Apple iPhone OS≥ 13.0 < 14.8 · < 12.5.5
Apple macOS< 11.6
Debian Linux10.0 · 11.0
Fedoraproject Fedora33 · 34

Remediation

Fixed in
Apple iPadOS≥ 14.8
Apple iPhone OS≥ 14.8
Apple macOS≥ 11.6

References

and 9 more references

Related CVEs

Recent high-severity vulnerabilities sharing a weakness type.

CVE-2026-859658.0
Progress MarkLogic Server 12.x releases before 12.1.0 and 11.x releases before 11.3.7…
CVE-2026-57599.8
A double free and use-after-free vulnerability in the RdbLoadDeletedNodes function of…
CVE-2026-1071838.1
llama.cpp before b11393 contains a use-after-free and double free vulnerability in…
CVE-2026-553309.8
In BluetoothCccHandlerCallbackImpl of bluetooth_ccc.cc, there is a possible…
CVE-2026-1064238.8
Use after free in Media in Google Chrome prior to 155.0.8059.39 allowed a remote…
CVE-2026-1064218.8
Use after free in PDF in Google Chrome prior to 155.0.8059.39 allowed a remote attacker…

Frequently asked

Is CVE-2021-30858 being actively exploited?

Yes. CVE-2021-30858 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added 3 Nov 2021.

How severe is CVE-2021-30858?

CVE-2021-30858 has a CVSS 3.1 base score of 8.8, rated high. EPSS estimates a 13.4% probability of exploitation.

Which products are affected by CVE-2021-30858?

Affected products include Apple iPadOS, Apple iPhone OS, Apple macOS, Debian Linux, Fedoraproject Fedora.

How do I fix CVE-2021-30858?

Upgrade affected software to a fixed version, for example Apple iPadOS 14.8, Apple iPhone OS 14.8, Apple macOS 11.6 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2021-30858 against the real software inventory on every managed device, as each hourly inventory arrives. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. Because it is on the CISA KEV list, a risk for it never ranks below high, and the update that fixes it moves to the Emergency patch lane. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

See how prioritisation worksBook a demo

Get Patch this first every Monday

Five vulnerabilities that matter this week, ranked on real exploitation. Plain language, one email, no spam.

You can unsubscribe with one click from every issue. We handle your details as described in our privacy policy.

Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.