CVE-2021-30858: Apple iOS, iPadOS, macOS Use-After-Free Vulnerability
Actively exploited. At least one CVE in this advisory is listed in the CISA Known Exploited Vulnerabilities catalog — exploitation has been observed in the wild. Treat remediation as urgent.
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.
CSIRTS triage
- What
- A use-after-free vulnerability in WebKit leads to code execution when processing malicious web content.
- Who is affected
- Users of Apple iOS, iPadOS, and macOS with WebKit.
- Urgency
- Remediation is urgent due to active exploitation and critical severity.
- Action
- Update to the latest version of iOS, iPadOS, or macOS.
AI-assisted analysis generated from the source advisory — verify against the original.
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Details
Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2021-30858
Exploitation outlook
EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.
- Exploitation confirmedCVE-2021-30858Already exploited in the wild (CISA KEV) — the prediction phase is over. Patch now. Riskier than 96% of all EPSS-scored CVEs.
Referenced CVEs
| CVE | CSIRTS overview | External |
|---|---|---|
| CVE-2021-30858 | coverage & exploitation status | NVD · CVE.org |
Recent advisories for Apple iOS
A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.
- high[NEW] [high] Apple macOS, iOS and iPadOS: Multiple vulnerabilitiescert-bund · 2026-08-25
- unknownNCSC-2026-0319 [1.00] [M/H] Vulnerabilities resolved in Apple iOS and iPadOSncsc-nl · 2026-08-20
- medium[NEW] [medium] Apple iOS and iPadOS: Multiple vulnerabilitiescert-bund · 2026-07-28
- unknownNCSC-2026-0266 [1.00] [M/H] Vulnerabilities fixed in Apple iOS and iPadOSncsc-nl · 2026-07-28
- unknownNCSC-2026-0215 [1.00] [M/H] Vulnerabilities fixed in Apple iOS and iPadOSncsc-nl · 2026-06-30
- criticalexploitedCVE-2023-41974: Apple iOS and iPadOS Use-After-Free Vulnerabilitycisa-kev · 2026-03-05
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