Should you update to Adobe Acrobat Reader 26.001.21662?
No: install Adobe Acrobat Reader 26.002.21901 instead. Adobe Acrobat Reader 26.001.21662 is a security update Adobe released on 9 Jun 2026 for Mac and Windows. It fixes 21 security flaws, 16 rated critical and 5 important by Adobe.[1] None of them is known to be used in attacks.
It has since been replaced by Adobe Acrobat Reader 26.002.21901, released 8 Sep 2026, which includes all of its fixes. If you’re on an older version, install that instead.
Should you update?
No: install Adobe Acrobat Reader 26.002.21901 instead. Adobe Acrobat Reader 26.002.21901 came out on 8 Sep 2026 and includes every fix in Adobe Acrobat Reader 26.001.21662, so there’s no reason to stop at this one. Software Update offers the newest version your device can run.
Is Adobe Acrobat Reader 26.001.21662 still safe?
Not any more. Adobe Acrobat Reader 26.002.21901 fixes 32 security flaws that Adobe Acrobat Reader 26.001.21662 doesn’t, and each became public the day its fix shipped. Installing it is safe: get it only from Reader’s own Check for Updates, never from a link in an email, text or pop-up.
What it fixes
Adobe lists 21 security flaws, 16 rated critical and 5 important by Adobe.[1] The 21 critical and important ones are:
| Flaw | Severity | What Adobe calls it |
|---|---|---|
CVE-2026-47911 | Critical | Out-of-bounds Write |
CVE-2026-47965 | Critical | Out-of-bounds Write |
CVE-2026-47912 | Critical | Use After Free |
CVE-2026-47913 | Critical | Use After Free |
CVE-2026-47914 | Critical | Use After Free |
CVE-2026-47915 | Critical | Use After Free |
CVE-2026-47916 | Critical | Use After Free |
CVE-2026-47917 | Critical | Use After Free |
CVE-2026-47918 | Critical | Use After Free |
CVE-2026-47919 | Critical | Use After Free |
CVE-2026-47920 | Critical | Use After Free |
CVE-2026-47921 | Critical | Use After Free |
CVE-2026-47955 | Critical | Use After Free |
CVE-2026-47959 | Critical | Stack-based Buffer Overflow |
CVE-2026-47952 | Critical | Heap-based Buffer Overflow |
CVE-2026-47937 | Critical | Uncontrolled Search Path Element |
CVE-2026-47961 | Important | Out-of-bounds Read |
CVE-2026-47923 | Important | Out-of-bounds Read |
CVE-2026-47924 | Important | Use After Free |
CVE-2026-47925 | Important | Integer Overflow or Wraparound |
CVE-2026-47926 | Important | Out-of-bounds Read |
How to update, and how long it takes
A few minutes. Reader restarts.
- Open Acrobat Reader.Choose Help → Check for Updates.
- Let it install.Close any PDFs it asks about; Reader restarts when it’s done.
To check it worked: Choose Help → About Adobe Acrobat Reader (on a Mac, Acrobat Reader → About): it shows the version. It should say 26.002.21901 or later.
Before and after
- After: Adobe Acrobat Reader 26.002.21901, 8 Sep 2026, 32 security flaws
- Adobe Acrobat Reader updates, every release and the latest version
- Updates, the latest version of everything HARD tracks
References
- ^ Adobe. “Adobe security bulletin APSB26-63”, 9 Jun 2026.