How severe is CVE-2021-31010?

CVE-2021-31010 has a CVSS score of 7.5/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2021-31010?

Affected package information for CVE-2021-31010 is not yet fully mapped. Check the official advisory links for details.

How do I fix CVE-2021-31010?

No fixed release is recorded for CVE-2021-31010 yet. Track the upstream advisory, and apply the exposure-reduction steps below in the meantime.

How do I detect CVE-2021-31010 in my code and dependencies?

Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`).

How do I mitigate CVE-2021-31010 if there is no patch (or I can't update yet)?

Do not deserialise data from untrusted sources: where the format allows it, restrict deserialisation to an explicit allowlist of expected types, and prefer a data-only format (JSON, Protobuf) over one that can reconstruct arbitrary objects until you can upgrade.

Is CVE-2021-31010 actively exploited in the wild?

Yes. There are 4 known exploit references for CVE-2021-31010, including 4 in-the-wild exploitations observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2021-31010?

CVE-2021-31010 has an EPSS (Exploit Prediction Scoring System) score of 3.7%, placing it in the 90th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

Is CVE-2021-31010 in the CISA Known Exploited Vulnerabilities catalog?

Yes. CVE-2021-31010 (Apple iOS, macOS, watchOS Sandbox Bypass Vulnerability) was added to CISA's Known Exploited Vulnerabilities (KEV) catalog on 2022-08-25. CISA required all US federal civilian agencies to remediate this vulnerability by 2022-09-15. The required action was: Apply updates per vendor instructions. Being listed in the KEV catalog is the strongest possible confirmation of active exploitation — treat this as a critical priority.

What type of vulnerability is CVE-2021-31010?

CVE-2021-31010 is classified as Deserialization of Untrusted Data (CWE-502). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2021-31010 published, and has it been updated?

CVE-2021-31010 was published on August 24, 2021 and was last updated on October 21, 2025. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🛡️

CISA KEV · ACTIVELY EXPLOITED

HIGH severity

CVE-2021-31010

HIGH

CVE-2021-31010 is a high-severity (CVSS 7.5) Deserialization of Untrusted Data vulnerability. It is in CISA's Known Exploited Vulnerabilities catalog (added 2022-08-25) — treat it as actively exploited and patch now. No vendor fix is recorded yet; mitigation options are listed below.

A deserialization issue was addressed through improved validation. This issue is fixed in Security Update 2021-005 Catalina, iOS 12.5.5, iOS 14.8 and iPadOS 14.8, macOS Big Sur 11.6,…

Published

Aug 24, 2021

Updated

Oct 21, 2025

Affected

5 products

Patched

See advisory

Exploits

4 known

Exploitation data as of Oct 23, 2026 · OSV.dev, NVD, CISA KEV, FIRST.org (EPSS)

Exploitation Status

Actively exploited in the wild

Confirmed by CISA's Known Exploited Vulnerabilities catalog on 2022-08-25. Federal agencies were required to remediate by 2022-09-15.
CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.

Exploitation and automatability from CISA (KEV catalog and SSVC triage) for CVE-2021-31010.

EPSS Exploitation Probability

via FIRST.org ↗

3.7%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs90th percentile — riskier than 90% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2021-31010 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 395,249 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Description

A deserialization issue was addressed through improved validation. This issue is fixed in Security Update 2021-005 Catalina, iOS 12.5.5, iOS 14.8 and iPadOS 14.8, macOS Big Sur 11.6, watchOS 7.6.2. A sandboxed process may be able to circumvent sandbox restrictions. Apple was aware of a report that this issue may have been actively exploited at the time of release..

Affected Products

5 products · 22 configurations

ipadosapple

< 14.8

range

iphone osapple

≥ 14.0 && < 14.8

range

mac os xapple

≥ 10.15 && < 10.15.7

1 version

10.15.7

macosapple

≥ 11.0 && < 11.6

range

watchosapple

< 7.6.2

range

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

A deserialization issue was addressed through improved validation. This …

support.apple.comGoogle-sheetSep 2021

A deserialization issue was addressed through improved validation. This …

nvd.nist.govNVDMay 2022

A deserialization issue was addressed through improved validation. This …

modernmsp.ioAPIOct 2021

A deserialization issue was addressed through improved validation. This …

cisa.govCISAAug 2022

Detection & mitigation playbook

Vulnerability

Detect
Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`).
Remediation status
No fixed release is recorded for CVE-2021-31010 yet. Track the upstream advisory, and apply the exposure-reduction steps below in the meantime.
Mitigate without a patch
Do not deserialise data from untrusted sources: where the format allows it, restrict deserialisation to an explicit allowlist of expected types, and prefer a data-only format (JSON, Protobuf) over one that can reconstruct arbitrary objects until you can upgrade.

Frequently Asked Questions

O3 Security · Impact-Aware SCA

Is CVE-2021-31010 in your dependencies?

Find it across , including transitive dependencies.

Scan my dependencies How O3 SCA works

CVSS Score

7.5/10CVSS v3 base

Vector breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

High

Availability

None

Raw vector

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

CWE Classification

CWE-502Deserialization of Untrusted Data

Weaponization

No known public exploit tooling found.

Timeline

Disclosed

Aug 24, 2021

First exploit

Sep 13, 2021

KEV added

Aug 25, 2022

Last updated

Oct 21, 2025

Identifiers

CVE-2021-31010

References

Websupport.apple.com Websupport.apple.com Websupport.apple.com Websupport.apple.com Websupport.apple.com Webcisa.gov

Related vulnerabilities

This CVE is high severity; 6 of 8 other CVEs with CWE-502 are rated as high or higher (top: critical).

GHSA-673q-mjm6-r5xrCVE-2026-70035CVE-2026-83520CVE-2026-87697CVE-2026-106558CVE-2026-83557GHSA-2jx3-ff3v-j7jjCVE-2025-66455Browse all CWE-502

Provenance

Sources

OSV.devNVDCISA KEVFIRST.org (EPSS)

Last verifiedOct 21, 2025

CVE-2021-31010

Exploitation Status

Actively exploited in the wild

EPSS Exploitation Probability

How urgent is this, really

Where this sits among everything scored

Description

Affected Products

Detection & mitigation playbook

Detect

Remediation status

Mitigate without a patch

Frequently Asked Questions

Is CVE-2021-31010 in your dependencies?