Threats / Microsoft / CVE-2025-53770
CVE-2025-53770
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-08-04
Microsoft SharePoint vulnerability
Microsoft SharePoint Server on-premises contains a deserialization vulnerability (CWE-502) allowing remote code execution. This is a patch bypass for CVE-2025-49704 and is actively exploited in ransomware campaigns.
Verdict
Today item, not a backlog item.
Critical remote code execution vulnerability in SharePoint on-premises via unsafe deserialization. High exploitation activity and ransomware deployment observed. Patch bypass status indicates previous mitigations were insufficient.
CISA KEV Yes · 2025-07-205Ransomware use Flagged5EPSS 0.99979 (verify live)6Exploit Weaponized · public PoC7CVSS 9.83CISA SSVC Exploitation: active · Automatable: yes · Impact: total4
01
Is it exploitable?
— the evidence, ranked above the scoreExploit available
Fully weaponized — public exploit code is cataloged for this vulnerability.We link the existence of the exploit; we do not host or redistribute payloads.
Reported exploitation
210 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2025-07-20), flagged for known ransomware use.
Probability (EPSS)
EPSS 0.99979 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
CVSS 9.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:F/RL:W/RC:C) · Affected: Microsoft, SharePoint. Confirm exact fixed builds in the vendor advisory.CVSS — CNA-assigned (CVE.org), version 3.1, set at disclosure.
Weakness (CWE)
Mapped to CWE-502 Deserialization of Untrusted Data — weakness family: Injection.CWE — CNA-assigned (CVE.org); the weakness class drives how the flaw is exploited.
CISA SSVC (triage disposition)
Exploitation: active · Automatable: yes · Technical Impact: totalCISA's own stakeholder-specific triage inputs, published in the CVE record (CISA Coordinator role). NOTE: this is CISA's three decision points; the final Act/Attend/Track decision also requires a Mission & Well-being input not published here, so no overall decision is asserted.
Currency of the record
CISA added this to its KEV catalog the same day the CVE record was published.KEV lag = CISA-KEV dateAdded − CVE.org datePublished; a floor on how long the known-exploited flaw sat in the public record before the federal catalog listed it. Severity/weakness here is CNA- or CISA-assigned (current at disclosure), independent of NVD's analysis backlog.
Public exploit available
Public exploit tooling is catalogued for this CVE (a functional/weaponized public exploit). Catalog entries: Metasploit module, nuclei template. We link the catalog page(s) only — no payload or code is hosted or restated here.Link, never host — the catalog page is the source; basicsecurity.net does not redistribute payloads.
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
I craft a malicious serialized object and send it to an unauthenticated SharePoint endpoint.
Business
Attacker gains initial network access to a core collaboration platform without authentication.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I exploit unsafe deserialization to execute arbitrary code with SharePoint service privileges.
Business
Attacker achieves code execution within the trusted security context of the SharePoint application.
3
Lateral reach — past segmentation narrative 3
Attacker
I establish persistence and lateral movement across the on-premises infrastructure.
Business
Attacker pivots to sensitive data repositories and domain resources accessible from SharePoint.
4
Data at risk — exfiltration narrative 4
Attacker
I deploy ransomware payloads across connected systems and encrypt business-critical data.
Business
Operations halt; data becomes inaccessible; ransom demands issued; recovery costs and downtime escalate.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05