VulnerabilityPublished 30 Jan 2026Updated 2 Feb 2026

CVE-2026-25156: kohler hotcrp · Cross-site Scripting

Affects kohler hotcrpSource CVE Database V5

Not known to be exploited · CVSS 7.3 High · fixed in 3.2.1 : patch kohler hotcrp soon.

Data as of 26 Oct 2026, 10:12 UTC

CVSS 3.1 base score

7.3High

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

EPSS: 0.2% chance of exploitation in 30 days – higher than 19% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 3.2.1

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: Low
User Interaction: Required
Scope: Unchanged
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: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
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 30 Jan 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: 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 26 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.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, 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

Affected software

Product	Affected	Fixed in
kohlerhotcrp	Affected =3.2	Fixed in–
GitHubkohler/hotcrp`pkg:github/kohler/hotcrp`Other threats	Affected =3.2	Fixed in–

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

AI-suggested

European organizations should immediately upgrade HotCRP installations from version 3.2 to version 3.2.1 or later, where the vulnerability is patched and the 'save=0' inline rendering feature is removed. Until the upgrade is applied, administrators should restrict file upload types to exclude HTML and SVG formats and disable inline rendering of documents except for explicitly safe MIME types. Implement strict content security policies (CSP) to limit script execution from uploaded documents. Educate users to avoid clicking on suspicious document links within HotCRP. Regularly audit uploaded files for unauthorized content types and monitor API usage for anomalous behavior. Additionally, review and tighten user privileges to minimize the impact of compromised credentials. Employ web application firewalls (WAF) with rules targeting XSS payloads in document uploads. Finally, maintain up-to-date backups and incident response plans tailored to web application compromises.

Description

HotCRP is conference review software. HotCRP versions from October 2025 through January 2026 delivered documents of all types with inline Content-Disposition, causing them to be rendered in the user’s browser rather than downloaded. (The intended behavior was for only `text/plain`, `application/pdf`, `image/gif`, `image/jpeg`, and `image/png` to be delivered inline, though adding `save=0` to the document URL could request inline delivery for any document.) This made users who clicked a document link vulnerable to cross-site scripting attacks. An uploaded HTML or SVG document would run in the viewer’s browser with access to their HotCRP credentials, and Javascript in that document could eventually make arbitrary calls to HotCRP’s API. Malicious documents could be uploaded to submission fields with “file upload” or “attachment” type, or as attachments to comments. PDF upload fields were not vulnerable. A search of documents uploaded to hotcrp.com found no evidence of exploitation. The vulnerability was introduced in commit aa20ef288828b04550950cf67c831af8a525f508 (11 October 2025), present in development versions and v3.2, and fixed in commit 8933e86c9f384b356dc4c6e9e2814dee1074b323 and v3.2.1. Additionally, c3d88a7e18d52119c65df31c2cc994edd2beccc5 and v3.2.1 remove support for `save=0`.

Impact

For European organizations using HotCRP 3.2, especially academic institutions, research organizations, and conference organizers, this vulnerability poses a significant risk to the confidentiality and integrity of sensitive review data and user credentials. Exploitation could lead to unauthorized access to confidential submissions, manipulation of review outcomes, or disclosure of personal information of reviewers and authors. The ability to perform arbitrary API calls could further allow attackers to escalate privileges or disrupt conference workflows. Given the collaborative and international nature of academic conferences in Europe, such a compromise could damage reputations, violate data protection regulations like GDPR, and disrupt critical research dissemination processes. Although no known exploitation has been reported, the ease of exploitation via user interaction and the widespread use of HotCRP in European academic circles heighten the threat. The vulnerability does not affect availability directly but could indirectly impact service trust and continuity.

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).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 7 Feb 2026, 08:32 UTC

WeaknessesCWE-79

Technical details

References

Community reviews

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