VulnerabilityPublished 8 Apr 2026

CVE-2026-35169: aces Loris · Cross-site Scripting

Affects aces LorisSource CVE Database V5

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Not known to be exploited · CVSS 8.7 High : upgrade to 28.0.1 soon.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score

8.7High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.1% chance of exploitation in 30 days – higher than 4% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 28.0.1, 28.0.2, 27.0.3

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: Low
User Interaction: Required
Scope: Changed
Confidentiality: High
Integrity: High
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
User Interaction: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
Scope: Changed: An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 8 Apr 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 24 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade Loris to 28.0.1; aces/loris to 28.0.2 or 27.0.3.

Affected software

Product	Affected	Fixed in
acesLoris	Affected >=28.0.0 <28.0.1	Fixed in 28.0.1
GitHubaces/loris`pkg:github/aces/loris`Other threats	Affected <27.0.3 >=28.0.0 <28.0.2	Fixed in 27.0.3 28.0.2

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

This vulnerability is fixed in LORIS versions 27.0.3 and 28.0.1. Users should upgrade to these or later versions to remediate the issue. Patch status is not explicitly confirmed by a vendor advisory in the provided data, but the description states the issue is fixed in these versions. No additional mitigation steps are indicated.

Description

CVE-2026-35169 is a high-severity vulnerability in the aces LORIS web application affecting versions before 27.0.3 and between 28.0.0 and 28.0.1. The help_editor module did not properly sanitize certain user-supplied input, leading to a reflected cross-site scripting (XSS) vulnerability. This flaw could allow an attacker to execute arbitrary scripts if a user is tricked into following a malicious link. Additionally, the same input vector could enable an attacker to download arbitrary markdown files from an unpatched server.

Impact

Successful exploitation can lead to high impact including execution of arbitrary scripts in the victim's browser, potentially resulting in credential theft, session hijacking, or other malicious actions. Additionally, unauthorized download of markdown files could lead to information disclosure. There is no indication of denial of service or system-level compromise. No known exploits have been reported in the wild.

Summary

LORIS is a self-hosted web application for neuroimaging research data management. Versions prior to 27.0.3 and between 28.0.0 and 28.0.1 contain a reflected XSS vulnerability in the help_editor module due to improper sanitization of user input. This vulnerability allows attackers to execute arbitrary scripts in the context of a victim's browser when the victim follows a crafted link. Furthermore, the same input flaw can be exploited to download arbitrary markdown files from the server. The issue is addressed in versions 27.0.3 and 28.0.1 of LORIS.

CWE-79Improper Neutralization of Input During Web Page Generation (Cross-site Scripting) (opens in a new tab)
Base weaknessLikelihood of exploit: HighCWE Top 25 (2025): #1OWASP Top 10 A05:2025: Injection (opens in a new tab)
The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.
Architecture and Design · Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Implementation · Architecture and Design
Understand the context in which your data will be used and the encoding that will be expected. This is especially important when transmitting data between different components, or when generating outputs that can contain multiple encodings at the same time, such as web pages or multi-part mail messages.
Architecture and Design · Implementation · Attack Surface Reduction
Understand all the potential areas where untrusted inputs can enter your software: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any external systems that provide…
OWASP Cheat Sheets
Cross Site Scripting Prevention (opens in a new tab)
DOM based XSS Prevention (opens in a new tab)
Injection Prevention (opens in a new tab)
Abuse Case (opens in a new tab)
Deserialization (opens in a new tab)
OWASP ASVS 4.0.3
V5.3.3 (opens in a new tab)
V1.5.1 (opens in a new tab)
Attack patterns
XSS Using MIME Type Mismatch (opens in a new tab)
DOM-Based XSS (opens in a new tab)
Reflected XSS (opens in a new tab)
Stored XSS (opens in a new tab)
Cross-Site Scripting (XSS) (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-552Files or Directories Accessible to External Parties (opens in a new tab)
Base weaknessOWASP Top 10 A01:2025: Broken Access Control (opens in a new tab)
The product makes files or directories accessible to unauthorized actors, even though they should not be.
Implementation · System Configuration · Operation
When storing data in the cloud (e.g., S3 buckets, Azure blobs, Google Cloud Storage, etc.), use the provider's controls to disable public access.
OWASP Cheat Sheets
Authorization (opens in a new tab)
OWASP ASVS 4.0.3
V12.5.1 (opens in a new tab)
V12.4.1 (opens in a new tab)
V8.3.8 (opens in a new tab)
Attack patterns
Collect Data from Common Resource Locations (opens in a new tab)
Probe System Files (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

github.com/aces/Loris/security/advisories/GHSA-j2p3-58m2-v6q3 (opens in a new tab)

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 16 Apr 2026, 12:20 UTC

WeaknessesCWE-79, CWE-552

Technical details

References

Community reviews

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