Improper server-side validation in ScreenConnect extension framework
In versions of ScreenConnect™ prior to 25.8, server-side validation and integrity checks within the extension subsystem could allow the installation and execution of untrusted or arbitrary extensions by authorized or administrative users. Abuse of this behavior could result in the execution of custom code on the server or unauthorized access to application configuration data. This issue affects only the ScreenConnect server component; host and guest clients are not impacted. ScreenConnect 25.8 introduces enhanced server-side configuration handling and integrity checks to ensure only trusted extensions can be installed.
- Published
- Dec 11, 2025
- Updated
- Jun 17, 2026
- EPSS
- 0.4% · 28th percentile
- CWE
- CWE-494
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Report tools
Action score
36
Monitor
Low priority for now.
- CVSS
- 36 / 40 · 9.1 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.4%
CISA SSVC decision
- Exploitation
- none
- Automatable
- no
- Technical impact
- total
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- —
- CNA · ConnectWise
- 9.1
- NVD has not scored this yet; the score shown is the CNA’s.
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| connectwise | screenconnect | cpe:2.3:a:connectwise:screenconnect |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- connectwise screenconnectbefore 25.8.0.9438
Versions reported by the vendor
Affected version ranges reported by the assigning authority (ConnectWise). Independent of NVD's CPE analysis and usually ahead of it.
ConnectWise ScreenConnect
- All versions prior to 2025.8affected
Same product
connectwise: all recordsOther highest-scoring records for the same primary product.
- CVE-2024-1709Authentication bypass using an alternate path or channelKEV100Now
- CVE-2024-1708Improper limitation of a pathname to a restricted directory (“path traversal”)KEV92Now
- CVE-2026-84869ScreenConnect Client: Guest-to-Host File Execution via File-Transfer ActionsKEV69This week
- CVE-2025-3935ScreenConnect Exposure to ASP.NET ViewState Code InjectionKEV59Plan
- CVE-2026-3564ScreenConnect Instance Level Cryptographic Material Exposure36Monitor
- CVE-2025-14823Certificate Signing Extension Returns Encrypted Values21Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
No fix version is recorded for this entry. Check the references for vendor advisories.
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- Administrator privileges are required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- high · data can be read
- Integrity
- high · data or configuration can be modified
- Availability
- high · the service can be disrupted
Impact can extend beyond the vulnerable component (scope changes).
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- High
- User interaction
- None
- Scope
- Changed
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- High
Weakness class (CWE)
CWE-494 · Download of Code Without Integrity CheckCVSS vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
nvd-secondary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
- Software Integrity AttackCAPEC-184Low
- Malicious Software DownloadCAPEC-185Very High
- Malicious Software UpdateCAPEC-186High
- Malicious Automated Software Update via RedirectionCAPEC-187likelihood: High · High
- Malicious Manual Software UpdateCAPEC-533likelihood: Low · High
- Open-Source Library ManipulationCAPEC-538likelihood: Low · High
- Malicious Automated Software Update via SpoofingCAPEC-657likelihood: High · High
- Adversary in the Browser (AiTB)CAPEC-662likelihood: High · Very High
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpChange log
No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.
References
Vendor advisories and official records. Exploit/PoC links are deliberately left out.