Known exploited vulnerability · CISA KEV

CVE-2015-5123: Adobe Flash Player Use-After-Free Vulnerability

Use-after-free vulnerability in the BitmapData class in the ActionScript 3 (AS3) implementation in Adobe Flash Player allows remote attackers to execute code or cause a denial-of-service (DoS).

CVE-2015-5123

Exploited in the wild. Fix this first.

CISA added it to the Known Exploited Vulnerabilities catalog on 2022-04-13: attackers are using it right now.

CISA KEV: Listed; Added 2022-04-13 · federal fix-by 2022-05-04
EPSS (30 days): 19%; Higher than 97% of CVEs · 2026-11-01
CVSS v3.1: 9.8 Critical; CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

What CISA says

Adobe Flash Player Use-After-Free Vulnerability

The impacted product is end-of-life and should be disconnected if still in use.

NVD description · published 2015-07-14

Use-after-free vulnerability in the BitmapData class in the ActionScript 3 (AS3) implementation in Adobe Flash Player 13.x through 13.0.0.302 on Windows and OS X, 14.x through 18.0.0.203 on Windows and OS X, 11.x through 11.2.202.481 on Linux, and 12.x through 18.0.0.204 on Linux Chrome installations allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via crafted Flash content that overrides a valueOf function, as exploited in the wild in July 2015.

Full record on NVD

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How to check if you are exposed to CVE-2015-5123

Find every Adobe Flash Player system you or your clients run, including ones exposed to the internet. Those come first: CISA only lists flaws attackers are already using.
Compare each version with the fixed versions in the vendor advisory. Where no fix exists yet, apply the vendor’s mitigation or take the system off the internet.
Run a credentialed vulnerability scan to catch the systems you missed, then check that the next scan no longer reports CVE-2015-5123.

US federal agencies had to fix this by 2022-05-04. Everyone else should treat that deadline as a guide: if it has passed, this is overdue.

Affected versions

Versions the National Vulnerability Database lists as vulnerable to CVE-2015-5123. Check the vendor advisory for the exact fixed builds before you sign anything off.

Product	Vulnerable versions
Adobe Flash Player	from 11.0 up to and including 11.2.202.481; from 13.0 up to and including 13.0.0.302; from 18.0 up to and including 18.0.0.203
Adobe Flash Player Desktop Runtime	from 18.0 up to and including 18.0.0.203
Redhat Enterprise Linux Desktop	5.0; 6.0
Redhat Enterprise Linux Server	5.0; 6.0
Redhat Enterprise Linux Server EUS	6.6
Redhat Enterprise Linux Workstation	5.0; 6.0

NVD lists 3 more affected products; see the full record on NVD.

Timeline

2015-07-14 · Published in the National Vulnerability Database
2022-04-13 · Added to CISA's Known Exploited Vulnerabilities catalog, 2,465 days after it was published
2022-05-04 · Fix-by date for US federal agencies, passed 1,642 days ago

Weakness type

CWE-416

More exploited Adobe vulnerabilities

CISA lists 83 exploited Adobe vulnerabilities. The closest matches:

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Sources: CISA Known Exploited Vulnerabilities catalog (version 2026.10.30); EPSS data from FIRST.org; CVSS and descriptions from the NIST National Vulnerability Database. Checked 2026-11-01. This product uses the NVD API but is not endorsed or certified by the NVD.