LocalSend is Vulnerable to Man-in-the-Middle Attacks, Leading to File Interception
LocalSend is an open-source app to securely share files and messages with nearby devices over local networks without needing an internet connection. In versions 1.16.1 and below, a critical Man-in-the-Middle (MitM) vulnerability in the software's discovery protocol allows an unauthenticated attacker on the same local network to impersonate legitimate devices, silently intercepting, reading, and modifying any file transfer. This can be used to steal sensitive data or inject malware, like ransomware, into files shared between trusted users. The attack is hardly detectable and easy to implement, posing a severe and immediate security risk. This issue was fixed in version 1.17.0.
- Published
- Aug 1, 2025
- Updated
- Jun 17, 2026
- EPSS
- 0.3% · 16th percentile
- CWE
- CWE-300
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Report tools
Action score
37
Monitor
Low priority for now.
- CVSS
- 37 / 40 · 9.3 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.3%
CISA SSVC decision
- Exploitation
- proof of concept
- Automatable
- no
- Technical impact
- total
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- —
- CNA · GitHub_M
- 9.3
- NVD has not scored this yet; the score shown is the CNA’s.
CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:N/SC:H/SI:H/SA:H
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| localsend | localsend | cpe:2.3:a:localsend:localsend |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- localsend localsendbefore 1.17.0
Versions reported by the vendor
Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.
localsend localsend
- <= 1.17.0affected
Same product
localsend: all recordsOther highest-scoring records for the same primary product.
- CVE-2025-27142LocalSend path traversal vulnerability in the file upload endpoint allows nearby devices to execute arbitrary commands25Monitor
- CVE-2026-25154LocalSend has Stored XSS in Web Share Interface via Filename24Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| localsend localsend | 1.17.0 · description | Vendor (CNA) |
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.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
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
- Someone on the same network segment can trigger it.
- No account or password is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- Integrity
- Availability
- Attack vector
- Adjacent
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- P
- Scope
- X
Weakness class (CWE)
CWE-300 · Channel Accessible by Non-EndpointCVSS vector
CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:N/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
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)
- Leveraging Active Adversary in the Middle Attacks to Bypass Same Origin PolicyCAPEC-466Medium
- Utilizing REST's Trust in the System Resource to Obtain Sensitive DataCAPEC-57likelihood: Medium · Very High
- DNS BlockingCAPEC-589
- IP Address BlockingCAPEC-590likelihood: Low · High
- WiFi MAC Address TrackingCAPEC-612Low
- WiFi SSID TrackingCAPEC-613Low
- Evil Twin Wi-Fi AttackCAPEC-615Low
- 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
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- github.com/localsend/localsend/commit/e8635204ec782ded45bc7d698deb60f3c4105687
- github.com/localsend/localsend/releases/tag/v1.17.0
Vendor advisories and official records. Exploit/PoC links are deliberately left out.