CVE-2026-26993Public exploitNetwork attack vector

Stored XSS via unsandboxed raw file preview

Published Feb 20, 2026 · Updated Feb 20, 2026

Stored XSS in Flare 1.7.0 and earlier allows remote authenticated users to run script in a visitor's browser through raw file preview. The raw-file routes return uploaded active content inline under its stored MIME type without a CSP sandbox or nosniff protection. Exploitation requires a valid uploader account and a visitor who opens the shared file and clicks Raw; the script can steal session data or act as that visitor.

CVSS severity4.6
Medium
EPSS probability0.28%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in Flare 1.7.0 and earlier allows remote authenticated users to run script in a visitor's browser through raw file preview. The raw-file routes return uploaded active content inline under its stored MIME type without a CSP sandbox or nosniff protection. Exploitation requires a valid uploader account and a visitor who opens the shared file and clicks Raw; the script can steal session data or act as that visitor.

The record

CVE
CVE-2026-26993
Published
Feb 20, 2026
Updated
Feb 20, 2026
Vendor
FlintSH
Product
Flare
Classifications
CWE-79, T1203
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 20, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 20, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1.7.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

FlintSH · Flareversion=1.7.1

Published CVSS scores

4.6GitHubCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N
5.4NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1203Exploitation for Client Execution

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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