Microsoft SharePoint: attackers can run their own code
OFFICIAL NAME: Microsoft SharePoint Code Injection Vulnerability
WHAT IT IS · DOCUMENTS AND COLLABORATIONIt holds shared documents and internal pages.
DO THIS FIRSTPatch it, or ask your provider whether they have. Not sure if you use it? Send this page to your IT provider or security lead and ask.
TECHNICAL SUMMARY Microsoft SharePoint contains a code injection vulnerability which could allow an authorized attacker to execute code over a network.
WHY THIS VERDICT Attacks are confirmed. The vulnerability is 91 days old, so many systems are likely still unpatched.
WHY IT RANKS HERE Exploitation is confirmed by an authoritative source. 4 products are affected.
- HIGHEST CONFIRMED RUNG
- EXPLOITED
- CISA KEV
- LISTED
- EXPLOIT CODE
- PROOF OF CONCEPT
How far has it climbed?
01 TALK
▨ REPORTED, NOT CONFIRMEDNEWEST EVIDENCE · 1 SOURCECVE-2026-65660 discussed publicly (CIRCL sighting). CVE-2026-65660 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.
04 EXPLOITED
■ CONFIRMEDNEWEST EVIDENCE · 2 INDEPENDENT SOURCESMicrosoft SharePoint contains a code injection vulnerability which could allow an authorized attacker to execute code over a network. CISA Vulnrichment marks CVE-2026-65660 as actively exploited.
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 PUBLIC
- 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 28, 2026, has passed. It is a US government deadline; use it as a guide.
Questions to ask this week
- Do we run Microsoft SharePoint? 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. AUG 11, 2026CISA Vulnrichment marks CVE-2026-65660 as actively exploited
- Attack activity. SEP 24, 2026Microsoft SharePoint Code Injection Vulnerability
- SEP 24, 20262 public GitHub repositories claim a proof of concept for CVE-2026-65660
- SEP 25, 2026Vulnerability CVE-2026-65660 confirmed by a researcher (CIRCL sighting)
- OCT 24, 2026CVE-2026-65660 discussed publicly (CIRCL sighting) (6 reports, latest NOV 5)
SOURCES
- [1] CIRCL Vulnerability-Lookup sightings: CVE-2026-65660 discussed publicly (CIRCL sighting), NOV 5
- [2] CIRCL Vulnerability-Lookup sightings: Vulnerability CVE-2026-65660 confirmed by a researcher (CIRCL sighting), SEP 25
- [3] PoC-in-GitHub: 2 public GitHub repositories claim a proof of concept for CVE-2026-65660, SEP 24
- [4] CISA Known Exploited Vulnerabilities: Microsoft SharePoint Code Injection Vulnerability, SEP 24
- [5] CVE List V5 and CISA Vulnrichment: CISA Vulnrichment marks CVE-2026-65660 as actively exploited, AUG 11
- [6] CIRCL Vulnerability-Lookup sightings: 5 more reports