Background exploitation KEV catalog No authentication
CVE-2016-4657

Apple iOS Webkit Memory Corruption Vulnerability

WebKit in Apple iOS before 9.3.5 allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via a crafted web site.

CheckOps priority index
7.9/10 Patch within 7 days
Severity8.8
Probability6.7
Exploitation4/5

Severity = CVSS. Probability = EPSS (FIRST). Exploitation = public signals: KEV, EUVD, ransomware, EPSS above 10 %, no account required.

EPSS · today 66.8% higher than 99.3% of CVEs
CVSS 3.1 8.8 AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:
Exploited for 1,624 days 24 May 2022
CISA due date 14 Jun 2022 for US federal agencies

Exploitation probability EPSS · FIRST

05010026 Sep05 Oct15 Oct24 Oct02 Nov
EPSS probability (%)Percentile among all CVEs

Exploitation signals 4 / 5

  • KEV catalog (CISA)24 May 2022
  • Exploited in EUVD (ENISA)24 May 2022
  • Used by ransomwareno
  • EPSS above 10 %66.8%
  • No account, over the networkyes

What to do

Fix

Apply the vendor’s fix as soon as it is available.

CISA guidance: Apply updates per vendor instructions.

Meanwhile

Take the service off the internet or restrict access to it, watch the logs and look for signs of compromise.

Manufacturers (CRA)

Exploited vulnerability in your product: early warning to ENISA within 24 h, then notification within 72 h (Article 14 of the Cyber Resilience Act). The CRA explained

Affected products

iOS
Weaknesses (CWE)

Open source packages OSV

Affected libraries according to OSV, with fixed versions.

Timeline

  1. Published

  2. Exploitation reported (ENISA)

  3. Added to the KEV catalog

  4. CISA remediation due date

  5. EPSS peak: 66.8%

References

Other exploited vulnerabilities from the same vendor

  • CVE-2026-86950Apple Multiple Products Out-of-Bounds Write Vulnerability
    6.7 · Actively exploited
  • CVE-2026-65400Apple macOS Improper Authentication Vulnerability
    5.8 · Actively exploited
  • CVE-2025-43520Apple Multiple Products Classic Buffer Overflow Vulnerability
    3.4 · Background exploitation
  • CVE-2025-43510Apple Multiple Products Improper Locking Vulnerability
    4.3 · Background exploitation
  • CVE-2025-31277Apple Multiple Products Buffer Overflow Vulnerability
    5.4 · Background exploitation
  • CVE-2023-43000Apple Multiple products Use-After-Free Vulnerability
    5.4 · Background exploitation

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Sources: CISA KEV · ENISA EUVD · FIRST EPSS · OSV. Public data aggregated by CheckOps, updated automatically. Source texts remain the property of their authors. All exploited vulnerabilities