7JUN

SharePoint patch clock runs out today

2 min read

10:08UTC

CISA gave federal agencies three days to remediate an actively exploited SharePoint code-execution flaw, with today's deadline the tightest on the catalogue.

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Key takeaway

SharePoint's three-day KEV deadline lands today, the tightest federal patch clock of the fortnight.

CISA, the US federal cyber-defence agency, added CVE-2026-45659, a remote-code-execution (RCE) flaw in Microsoft SharePoint Server, to its Known Exploited Vulnerabilities (KEV) catalogue on Wednesday 1 July, with a Federal Civilian Executive Branch (FCEB) remediation deadline of today, Saturday 4 July. That is a three-day window on the most widely deployed on-premises collaboration platform across government and enterprise estates. The catalogue lists ransomware use as "Unknown".⁠¹

The flaw falls under BOD 26-04, the risk-tiered Binding Operational Directive that replaced patch-by-deadline enforcement on 10 June. A deserialisation-of-untrusted-data vulnerability lets an attacker feed crafted input that the server rebuilds into running code, and SharePoint's ubiquity across on-premises estates is what makes a three-day clock uncomfortable. Nothing else on the catalogue this fortnight runs tighter.

Deep Analysis

In plain English

SharePoint is a Microsoft tool that companies and governments use to share documents and manage internal websites. A flaw was found in the version installed on an organisation's own servers, rather than Microsoft's version, that lets an attacker send it corrupted data and gain control of the machine. The US government's cyber-defence agency ordered its own agencies to fix the flaw within three days of listing it, an unusually tight deadline, even though nobody has yet confirmed a ransomware gang is actively using it. The urgency comes from experience: a similar SharePoint flaw last year was used to break into government and manufacturing networks worldwide within about two weeks of becoming public.

Deep Analysis

Root Causes

CISA's BOD 26-04, which replaced the flat two-week patching mandate of BOD 22-01 on 10 June, sorts vulnerabilities into risk tiers with compressed deadlines for internet-facing remote-code flaws; a three-day window here is the tiering working as designed, not an emergency exception.

Many federal agencies still run SharePoint Server on-premises rather than the cloud version, often because of data-residency rules or a decade of custom workflow additions, which keeps a legacy deserialisation attack surface alive long after Microsoft's own roadmap pushed customers toward the hosted product.

What could happen next?

Risk
Agencies still running on-premises SharePoint Server face the same three-day clock regardless of patch-testing capacity, raising the odds some will remediate late, as happened with the Splunk and Ubiquiti deadlines this same fortnight (ID:4471, ID:4473).
Precedent
If exploitation follows the ToolShell timeline, ransomware use could move from Unknown to confirmed within two to three weeks of the 1 July listing.

Source Landscape

This story draws on neutral-leaning sources

Primary parallel: July 2025's 'ToolShell' SharePoint on-premises exploit chain (CVE-2025-53770) went from its exploited-vulnerability listing to mass ransomware use by the Warlock and Storm-2603 crews within roughly two weeks, hitting government and manufacturing targets worldwide.

Counter-parallel: 2019's SharePoint deserialisation bug, CVE-2019-0604, stayed confined to a handful of targeted espionage intrusions linked to the China-based APT27 group rather than becoming a mass event, because Microsoft's patch reached most customers before public proof-of-concept code circulated.

Consensus view: Rapid7's Caitlin Condon assesses that the three-day federal remediation window, 1 to 4 July, is unusually compressed for a deserialisation bug and reflects CISA applying its BOD 26-04 risk tiers aggressively, even though the catalogue entry itself lists ransomware use as Unknown.

Counter-view: China's Qihoo 360 Netlab team argues the compressed deadline reacts to confirmed exploitation rather than anticipating it, and notes that SharePoint's deserialisation flaw class has recurred since 2019 without Microsoft closing the underlying design pattern that keeps producing it.

Key tension: Whether a three-day remediation clock without a confirmed ransomware link protects agencies ahead of exploitation, or simply outruns their patch-testing cycles and pushes some to miss the deadline entirely.

Sources:CISA

Mentions:FCEB →Microsoft →China →CISA →CVE-2026-45247 →Microsoft SharePoint →BOD 26-04 →Rapid7 →Known Exploited Vulnerabilities →Binding Operational Directive →

First Reported In

Update #9 · FortiBleed harvest linked to Lynx crew

CISA· 4 Jul 2026

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Causes and effects

Caused by

CISA tears up its KEV deadline rules

BOD 26-04's risk-tiered framework set the remediation window applied to the SharePoint deserialisation flaw.

Occurred 10 Jun 2026

Read story →

This Event

SharePoint patch clock runs out today

A three-day deadline on the most widely deployed on-premises collaboration server is the first hard test of how fast agencies can move under the new triage regime.

Led to

SharePoint stays under active KEV fire

CISA's three-day SharePoint deserialisation KEV deadline set on 1 July is escalated by two further SharePoint deserialisation CVEs landing on 16 and 22 July.

Occurred 22 Jul 2026

Read story →

Different Perspectives

Hospital Sírio-Libanês

Hospital Sírio-Libanês said a 21 September attack reached a reporting system for its social projects, possibly exposing patients' and staff identity numbers and health information, while its general patient database was untouched. It notified the ANPD and the Polícia Federal and warned of fraud attempts.

The Foschini Group

The Foschini Group told the Johannesburg exchange on 13 October that an attack found on 11 October disrupted IT systems at its TFG London brands, while stores stayed open. It has not identified the attackers or established whether personal data was taken.

FirstVDS

FirstVDS said attackers used a VMmanager 6 flaw to copy customers' passwords, cloud credentials and cryptocurrency wallets from beneath their virtual servers, and told notified customers to assume theft and rotate credentials. ISPsystem's flaw was not fully fixed on 19 October.

ESET

ESET says Russia-aligned UAC-0099 phished a Ukrainian grain logistics firm in July 2025 and apparently passed its access to GRU-linked Sandworm, which wiped the company's data that September. It treats the attackers' use of the Yggdrasil network as a first for a state-aligned actor.

JPCERT/CC

JPCERT/CC issued emergency alert AT-2026-0032 on 14 October as EG Secure Solutions confirmed attacks on the SiteGuard Server Edition flaw. It told operators to save diagnostic data before updating, because the update may erase traces of the attack.

Cyber Security Agency of Singapore

The Cyber Security Agency of Singapore said on 20 October that attackers are exploiting Ivanti Connect Secure, seven days after Ivanti's disclosure, having flagged PAN-OS exploitation on 16 October. It issued a PHP2Shell alert on 21 October, the day the fixes shipped.

Written with AI from Lowdown's published reporting. Not individually reviewed by an editor. Editorial standards.