What is CVE-2016-4657?

CVE-2016-4657 is a high-severity vulnerability in Apple Iphone OS, classified under Out-of-bounds Write. CVSS score: 8.8/10. Published 2016-08-25.

How severe is CVE-2016-4657?

High severity. CVSS v3 base score is 8.8 out of 10.

Is CVE-2016-4657 known to be exploited?

Yes. CVE-2016-4657 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2022-05-24), indicating it is being actively exploited. 19 public proof-of-concept repositories are indexed.

Buffer overflow in Apple Iphone OS

CVE-2016-4657

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.

Vulnerability class: Buffer Overflow

Published 2016-08-25 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.668 (99.3th percentile), scored 2026-10-19.

High probability of exploitation in the next 30 days — patch promptly. 99th percentile — 99.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.668 · newest: 0.668 · change: 0.000

Affected products

Apple Iphone OS

Weakness classification (CWE)

CWE-787 — Out-of-bounds Write

CISA KEV (Known Exploited Vulnerabilities)

This CVE is on the CISA KEV catalog, added on 2022-05-24. CISA KEV inclusion means CISA has confirmed in-the-wild exploitation; US federal agencies are required to remediate within a published due date.

BOD 22-01 due date: 2022-06-14.

Required action: Apply updates per vendor instructions.

Public proof-of-concept exploits

References

blog.lookout.com/blog/2016/08/25/trident-pegasus/ (Broken Link)
www.youtube.com/watch (Exploit)
www.exploit-db.com/exploits/44836/ (Exploit, VDB Entry, Third Party Advisory, exploit)
www.securityfocus.com/bid/92653 (VDB Entry, Third Party Advisory, vdb-entry, Broken Link)
support.apple.com/HT207107 (Release Notes, Vendor Advisory)
lists.apple.com/archives/security-announce/2016/Aug/msg00000.html (vendor-advisory, Mailing List, Broken Link, Vendor Advisory)
www.securitytracker.com/id/1036694 (VDB Entry, Third Party Advisory, vdb-entry, Broken Link)
134c704f-9b21-4f2e-91b3-4a467353bcc0 (US Government Resource)

Frequently asked questions

What is CVE-2016-4657?: CVE-2016-4657 is a high-severity vulnerability in Apple Iphone OS, classified under Out-of-bounds Write. CVSS score: 8.8/10. Published 2016-08-25.
How severe is CVE-2016-4657?: High severity. CVSS v3 base score is 8.8 out of 10.
Is CVE-2016-4657 known to be exploited?: Yes. CVE-2016-4657 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2022-05-24), indicating it is being actively exploited. 19 public proof-of-concept repositories are indexed.