CVE-2016-4657 [Exploited] | Apple IPHONE OS Out-of-bounds Write

CVE-2016-4657 is rated Critical Active Threat (96/100): CVSS High severity, with high exploitation likelihood (EPSS 79.43%, 99th percentile). CISA KEV confirms active exploitation (added 2022-05-24) affecting Apple / iOS. a weakness (CWE-787) Unauthenticated remote administrative access may be possible. EPSS rose +1.09% over the last day, indicating growing attacker interest. The CISA remediation deadline has passed—treat as an emergency patch priority.

EDB-ID	Source	Kind	Published	Link
44836	exploit_db	edb	2018-06-05	Exploit-DB ↗
44213	exploit_db	edb	2017-03-12	Exploit-DB ↗
—	nvd_ref	exploit_tag		Exploit-DB ↗
—	nvd_ref	exploit_tag		Exploit-DB ↗

EDB-ID

Source

Kind

Published

Link

44836

exploit_db

edb

2018-06-05

Exploit-DB ↗

44213

exploit_db

edb

2017-03-12

Exploit-DB ↗

—

nvd_ref

exploit_tag

Exploit-DB ↗

—

nvd_ref

exploit_tag

Exploit-DB ↗

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-04-24	78.34%	79.43%	+1.09%
2	2026-04-22	77.13%	78.34%	+1.22%
3	2026-03-16	—	77.13%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-04-24

78.34%

79.43%

+1.09%

2026-04-22

77.13%

78.34%

+1.22%

2026-03-16

—

77.13%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
8.8	3.1	HIGH	`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:R) A real person has to do something—click, install, enable—otherwise it doesn’t land. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:H) Serious risk that confidential data gets exposed in a big way. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	2.8	5.9	[email protected]
8.8	3.1	HIGH	`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:R) A real person has to do something—click, install, enable—otherwise it doesn’t land. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:H) Serious risk that confidential data gets exposed in a big way. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	2.8	5.9	134c704f-9b21-4f2e-91b3-4a467353bcc0
6.8	2.0	MEDIUM	`AV:N/AC:M/Au:N/C:P/I:P/A:P` Click to expand Access vector (AV:N) Can be exploited remotely over network reachability. Access complexity (AC:M) Exploitation needs some favorable conditions, but not exceptional ones. Authentication (AU:N) No authentication is required. Confidentiality impact (C:P) Partial confidentiality impact. Integrity impact (I:P) Partial integrity impact. Availability impact (A:P) Partial availability impact.	8.6	6.4	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

8.8

3.1

HIGH

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

Attack vector (AV:N): Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N): No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R): A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H): Serious risk that confidential data gets exposed in a big way.
Integrity (I:H): They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

2.8

5.9

[email protected]

8.8

3.1

HIGH

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

Attack vector (AV:N): Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N): No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R): A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H): Serious risk that confidential data gets exposed in a big way.
Integrity (I:H): They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

2.8

5.9

134c704f-9b21-4f2e-91b3-4a467353bcc0

6.8

2.0

MEDIUM

AV:N/AC:M/Au:N/C:P/I:P/A:P Click to expand

Access vector (AV:N): Can be exploited remotely over network reachability.
Access complexity (AC:M): Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N): No authentication is required.
Confidentiality impact (C:P): Partial confidentiality impact.
Integrity impact (I:P): Partial integrity impact.
Availability impact (A:P): Partial availability impact.

8.6

6.4

[email protected]

OS Trackers for CVE-2016-4657

vendor	priority	summary	link
`ubuntu`	medium	CVE-2016-4657 medium priority: Ubuntu including 5 source packages (qtwebkit-opensource-src, qtwebkit-source, webkit, webkit2gtk, webkitgtk), 25 status rows across 5 suites (precise, trusty, upstream, xenial, yakkety): DNE 10, ignored 8, needs-triage 4, released 2, not-affected 1.	https://ubuntu.com/security/CVE-2016-4657

Affected software / configurations for CVE-2016-4657

Vendor	Product	Version	Raw CPE
apple	iphone_os	< 9.3.5	cpe:2.3:o:apple:iphone_os::::::::

References for CVE-2016-4657

URL	Tags
http://lists.apple.com/archives/security-announce/2016/Aug/msg00000.html	Mailing List Vendor Advisory Broken Link
http://www.securityfocus.com/bid/92653	Broken Link Third Party Advisory VDB Entry
http://www.securitytracker.com/id/1036694	Broken Link Third Party Advisory VDB Entry
https://blog.lookout.com/blog/2016/08/25/trident-pegasus/	Broken Link
https://support.apple.com/HT207107	Release Notes Vendor Advisory
https://www.exploit-db.com/exploits/44836/	Exploit Third Party Advisory VDB Entry
https://www.youtube.com/watch?v=xkdPjbaLngE	Exploit
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2016-4657	US Government Resource

URL

CVE-2016-4657

CISA KEV Record for CVE-2016-4657

Public exploit references (Exploit-DB) for CVE-2016-4657

Exploit prediction scoring system (EPSS) score for CVE-2016-4657

Common vulnerability scoring system (CVSS) metrics for CVE-2016-4657

Weakness enumeration for CVE-2016-4657

OS Trackers for CVE-2016-4657

Affected software / configurations for CVE-2016-4657

References for CVE-2016-4657