Microsoft Windows: 2 flaws used in attacks; attackers can gain admin rights
OFFICIAL NAMES: Microsoft Windows Heap-Based Buffer Overflow Vulnerability · Microsoft Windows Link Following Vulnerability
WHAT IT IS · COMPUTERS, PHONES AND BROWSERSIt runs on staff computers, phones or browsers.
DO THIS FIRSTInstall the latest updates on every device, and turn on automatic updates. Not sure if you use it? Send this page to your IT provider or security lead and ask.
TECHNICAL SUMMARY Microsoft Windows Update Stack contains a link following vulnerability that allows a local attacker to escalate privileges locally up to SYSTEM.
WHY THIS VERDICT Attacks are confirmed. The vulnerability is 60 days old, so current versions are being attacked.
- HIGHEST CONFIRMED RUNG
- EXPLOITED
- CISA KEV
- LISTED
- EXPLOIT CODE
- PROOF OF CONCEPT CLAIMED
How far has it climbed?
01 TALK
■ CONFIRMEDNEWEST EVIDENCE · 2 INDEPENDENT SOURCESCVE-2026-81963 discussed publicly (CIRCL sighting). CVE-2026-81963 discussed publicly (CIRCL sighting).
02 EXPOSED
□ NOT TRACKED YETNO SOURCE FOR THIS STEP YETWe have no source that counts exposed systems yet. Internet scan data needs a partnership we do not have. No evidence here does not mean nothing is exposed.
03 TRIED
■ CONFIRMEDNEWEST EVIDENCE · 2 INDEPENDENT SOURCESAttacks that worked are confirmed (step 4), so attempts count as confirmed too.
- SRC: CVE List V5 and CISA Vulnrichment: CISA Vulnrichment marks CVE-2026-81963 as actively exploited · SEP 8
- SRC: CVE List V5 and CISA Vulnrichment: CISA Vulnrichment marks CVE-2026-85880 as actively exploited · SEP 8
- SRC: CISA Known Exploited Vulnerabilities: Microsoft Windows Link Following Vulnerability · SEP 7
- SRC: CISA Known Exploited Vulnerabilities: Microsoft Windows Heap-Based Buffer Overflow Vulnerability · SEP 7
04 EXPLOITED
■ CONFIRMEDNEWEST EVIDENCE · 2 INDEPENDENT SOURCESCISA Vulnrichment marks CVE-2026-81963 as actively exploited. CISA Vulnrichment marks CVE-2026-85880 as actively exploited.
- SRC: CVE List V5 and CISA Vulnrichment: CISA Vulnrichment marks CVE-2026-81963 as actively exploited · SEP 8
- SRC: CVE List V5 and CISA Vulnrichment: CISA Vulnrichment marks CVE-2026-85880 as actively exploited · SEP 8
- SRC: CISA Known Exploited Vulnerabilities: Microsoft Windows Link Following Vulnerability · SEP 7
- SRC: CISA Known Exploited Vulnerabilities: Microsoft Windows Heap-Based Buffer Overflow Vulnerability · SEP 7
05 DAMAGE
□ NOT TRACKED YETNO SOURCE FOR THIS STEP YETBreach notices and filings rarely name the flaw that was used, so we cannot link them to this event yet. No evidence here does not mean no harm.
When each thing happened
- DISCLOSED
- EXPLOIT CODE PUBLICCLAIMED
- FIRST ATTACK REPORT
- CISA KEV LISTING
- US FEDERAL DEADLINE
THE FIX
CISA's instruction: apply the vendor's fix, or stop using the product if no fix exists. The deadline CISA set for US federal agencies, Sep 22, 2026, has passed. It is a US government deadline; use it as a guide.
Questions to ask this week
- Do we run Microsoft Windows? If yes, is it patched or cut off from the internet?
- Who owns fixing it, and by what date?
- Have we checked for signs of attack since the first report, not just since the patch?
How it unfolded
- Attack activity. SEP 7, 2026Microsoft Windows Link Following Vulnerability
- Attack activity. SEP 7, 2026Microsoft Windows Heap-Based Buffer Overflow Vulnerability
- Attack activity. SEP 8, 2026CISA Vulnrichment marks CVE-2026-85880 as actively exploited
- Attack activity. SEP 8, 2026CISA Vulnrichment marks CVE-2026-81963 as actively exploited
- SEP 8, 2026Microsoft Plugs Nearly 1,000 Security Holes
- OCT 19, 20261 public GitHub repository claims a proof of concept for CVE-2026-81963
- NOV 3, 2026CVE-2026-81963 discussed publicly (CIRCL sighting) (2 reports)
SOURCES
- [1] CIRCL Vulnerability-Lookup sightings: CVE-2026-81963 discussed publicly (CIRCL sighting), NOV 3
- [2] PoC-in-GitHub: 1 public GitHub repository claims a proof of concept for CVE-2026-81963, OCT 19
- [3] Krebs on Security: Microsoft Plugs Nearly 1,000 Security Holes, SEP 8
- [4] CVE List V5 and CISA Vulnrichment: CISA Vulnrichment marks CVE-2026-81963 as actively exploited, SEP 8
- [5] CVE List V5 and CISA Vulnrichment: CISA Vulnrichment marks CVE-2026-85880 as actively exploited, SEP 8
- [6] CISA Known Exploited Vulnerabilities: Microsoft Windows Link Following Vulnerability, SEP 7
- [7] CISA Known Exploited Vulnerabilities: Microsoft Windows Heap-Based Buffer Overflow Vulnerability, SEP 7
- [8] CIRCL Vulnerability-Lookup sightings: 1 more reports