CVE-2016-1021: n/a: Out-of-bounds Write

Recommended actionWithin 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available

What, why and how

Adobe Flash Player before 18.0.0.343 and 19.x through 21.x before 21.0.0.213 on Windows and OS X and before 11.2.202.616 on Linux allows attackers to execute arbitrary code or cause a denial of service (memory corruption) via unspecified vectors, a different vulnerability than CVE-2016-1012, CVE-2016-1020, CVE-2016-1022, CVE-2016-1023, CVE-2016-1024, CVE-2016-1025, CVE-2016-1026, CVE-2016-1027, CVE-2016-1028, CVE-2016-1029, CVE-2016-1032, and CVE-2016-1033.

What

Why

A bounds error lets data be written beyond the intended memory region, potentially corrupting control data.

How

An attacker operating through a network path may attempt exploitation without authentication after a user interaction. If successful, the issue may execute code or commands in the affected security context.

What

Why

A bounds error lets data be written beyond the intended memory region, potentially corrupting control data.

How

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation

Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.

No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material

Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.

None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path: a network path → Out-of-bounds Write → execute code or commands in the affected security context
Attack surface: Network
Privileges required: None: unauthenticated exploitation is possible
User interaction: Required interaction required
Attack complexity: Low: no specialised conditions are recorded
Security boundary: Unchanged: impact remains within the vulnerable component's security authority
Weakness ? CWE means Common Weakness Enumeration: a standard category for the underlying weakness.: CWE-787 ↗
CWE-787: Out-of-bounds Write. The product writes data past the end, or before the beginning, of the intended buffer.
CVSS vector ? CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.
AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UIRequiredUser interaction: Another user must perform an action for exploitation to succeed.SUnchangedScope: The security impact remains within the vulnerable component's authority.CHighConfidentiality impact: A successful attack can cause a major loss.IHighIntegrity impact: A successful attack can cause a major loss.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land: After compromise, an attacker may use built-in shells, scripting engines, scheduled tasks and native network utilities for discovery, persistence or movement. This is a plausible LoTL path, not evidence that it has occurred for every attack.

NetworkUnauthenticatedRemote code executionDenial of serviceCWE-787

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

ENISA EUVD · EUVD-2016-2125Official EUVD mapping

0 linked advisory records.

Official EUVD record ↗

Canadian Centre for Cyber Security · English · AV16-059security updates for Adobe Flash Player

Windows and Macintosh Adobe Flash Player Extended Support Release 18.0.0.333 and earlier for Windows and Macintosh Adobe Flash Player for Google Chrome 21.0.0.197 and earlier for Windows, Macintosh, Linux, and ChromeOS Adobe Flash Player for Microsoft Edge and Internet Explorer 11 21.0.0.197 and earlier for Windows 10 Adobe Flash Player for Internet Explorer 11 21.0.0.197 and earlier for Windows 8.1 Adobe Flash Player for Linux 11.2.202.577 and earlier for Linux CVE References: CVE-2016-1006, CVE-2016-1011, CVE-2016-1012, CVE-2016-1013, CVE-2016-1014, CVE-2016-1015, CVE-2016-1016, CVE-2016-1017, CVE-2016-1018, CVE-2016-1019*, CVE-2016-1020, CVE-2016-1021, CVE-2016-1022, CVE-2016-1023, CVE-2016-1024, CVE-2016-1025, CVE-2016-1026, CVE-2016-1027, CVE-2016-1028, CVE-2016-1029, CVE-2016-1030, CVE-2016-1031, CVE-2016-1032, CVE-2016-1033 *Adobe is aware that CVE-2016-1019 is being actively exploited in the wild on systems running Windows 10 and earlier with Flash Player version 20.0.0.306 and earlier. Please refer to CCIRC Alert AL16-006 for details. Suggested Action CCIRC recommends that system administrators test and deploy the vendor-released updates to affected applications accordingly. References: https://helpx.adobe.com/security/products/flash-player/apsb16-10.html http://www.publicsafety.gc.

n/a: Out-of-bounds Write

National CERT insights ?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

EUVD-2016-2125

What, why and how

Exploit reality and attack path

Official authority intelligence

Patch and workaround

Evidence and provenance

National CERT insights
?
CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.