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vulnerability

CVE-2021-30952

7.8
High
KEV · Exploited in wildEPSS 7%Patch available

An integer overflow was addressed with improved input validation. This issue is fixed in tvOS 15.2, macOS Monterey 12.1, Safari 15.2, iOS 15.2 and iPadOS 15.2, watchOS 8.3. Processing maliciously crafted web content may lead to arbitrary code execution.

exploited
Yes, in CISA KEV since 5 Mar 2026fix by 26 Mar 2026 (CISA deadline for US federal agencies)
fix
Patch available see the advisory in the references
likelihood
EPSS 7.0%
Published 24 Aug 2021Analysed here 2 Nov 2026

do firstApply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

triage
server-sideruntimeWAF can block: noAV · localCWE-190· Integer Overflow

Can a WAF block it? No. The attack needs local access to the machine, so a WAF is not on its path.

Also consider: patch

Based on the attack vector (local or physical access). We check Cloudflare, AWS, Google Cloud Armor and Azure; for Akamai, Imperva, Fastly, F5, ask your vendor.

cvss vector
attack vectorlocalattack complexitylowprivileges requirednoneuser interactionrequiredscopeunchangedconfidentialityhighintegrityhighavailabilityhigh
CVSS 3.1 · CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
common questions

Is CVE-2021-30952 being exploited?

Yes. CVE-2021-30952 appears in CISA's Known Exploited Vulnerabilities catalog, which means exploitation in the wild has been confirmed and reported. Treat it as active rather than theoretical, and patch it ahead of higher-scoring vulnerabilities that carry no exploitation evidence.

How severe is CVE-2021-30952?

CVE-2021-30952 is rated High with a CVSS score of 7.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.

Is there a patch for CVE-2021-30952?

Yes. A fix has been recorded for CVE-2021-30952. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.

What does CVE-2021-30952 affect?

CVE-2021-30952 affects apple:safari, apple:ipados, apple:iphone_os, apple:macos, and 6 further products or versions. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.

Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.

executive summary
technical analysis
affected
apple:safariapple:ipadosapple:iphone_osapple:macosapple:tvosapple:watchosfedoraproject:fedoradebian:debian_linuxwebkitgtk:webkitgtkwpewebkit:wpe_webkit
affected versions
Apple iOS and iPadOS
  • affected< 15.2
Apple macOS
  • affected< 12.1
  • affected< 15.2
Apple watchOS
  • affected< 8.3

As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.

cisa ssvc

exploitation
active
automatable
no
technical impact
total

Assessed by CISA 5 Mar 2026 (SSVC 2.0.3).

timeline

  1. 24 Aug 2021Published
  2. 5 Mar 2026Added to CISA KEV (exploited in the wild) · 1,653 days (about 5 years) later
  3. 5 Mar 2026CISA SSVC assessment: exploitation active · same day later
  4. 6 Mar 2026CVE record last updated · 1 day later
  5. 26 Mar 2026CISA remediation due date (US federal agencies) · 20 days later
  6. 2 Nov 2026Analysed by vulneraibility.com · 222 days (about 7 months) later
how to fix
Remediation steps are tailored for users whose stack is affected. Add this technology to your stack to see the fix checklist.
references
12 references in the CVE record: 5 advisories, 7 links
Show 4 more

sources

  • CVE List (CVE.org): description, affected versions, references; CVE Terms of Use
  • NVD: CVSS and CPE data
  • CISA KEV catalog: exploitation, date added, due date
  • CISA Vulnrichment (ADP): SSVC decision points
  • FIRST EPSS: exploit probability and percentile
  • Summary, impact and triage tags: written by our AI analysis pipeline from the sources above. Check them against the sources.
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