CVE-2026-35403Network attack vector

Reflected XSS via missing JSON Content-Type header

Published Apr 8, 2026 · Updated Apr 8, 2026

Reflected XSS in ACElab LORIS 15.10 through 27.0.2 and 28.0.0 allows remote authenticated users to execute script via an invalid visit label. ValidateEmailSubmitInput.php returns JSON-encoded error data without a JSON Content-Type header, so browsers parse a crafted response as HTML. The attacker needs survey_accounts access and a user must follow a crafted invalid link, exposing browser-accessible data and actions to injected script.

CVSS severity6.5
Medium
EPSS probability0.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reflected XSS in ACElab LORIS 15.10 through 27.0.2 and 28.0.0 allows remote authenticated users to execute script via an invalid visit label. ValidateEmailSubmitInput.php returns JSON-encoded error data without a JSON Content-Type header, so browsers parse a crafted response as HTML. The attacker needs survey_accounts access and a user must follow a crafted invalid link, exposing browser-accessible data and actions to injected script.

The record

CVE
CVE-2026-35403
Published
Apr 8, 2026
Updated
Apr 8, 2026
Vendor
ACElab
Product
LORIS
Classifications
CWE-79, T1203
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 8, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 8, 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=>= 15.10, < 27.0.3
  2. Affected versionversion=>= 28.0.0, < 28.0.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

ACElab · LORISversion=>= 15.10, < 27.0.3; version=>= 28.0.0, < 28.0.1

Published CVSS scores

6.5GitHub, Inc.CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/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 exploitUnconfirmed

Weakness, pattern, technique

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

Public exploit references

No public exploit references are available in this record.

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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