VulnerabilityPublished 4 Jun 2025

CVE-2025-31136: FreshRSS · Cross-site Scripting

Affects FreshRSSSource CVE Database V5

Not known to be exploited · CVSS 6.7 Medium : upgrade to 1.26.2 when convenient.

Data as of 26 Oct 2026, 17:16 UTC

CVSS 3.1 base score

6.7Medium

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

EPSS: 0.3% chance of exploitation in 30 days – higher than 30% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 1.26.2

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

Attack Vector: Network
Attack Complexity: High
Privileges Required: Low
User Interaction: Required
Scope: Unchanged
Confidentiality: High
Integrity: High
Availability: Low

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: High: A successful attack depends on conditions beyond the attacker's control. That is, a successful attack cannot be accomplished at will, but requires the attacker to invest in some measurable amount of effort in preparation or execution against the vulnerable component before a successful attack can be expected. For example, a successful attack may require an attacker to: gather knowledge about the environment in which the vulnerable target/component exists; prepare the target environment to improve exploit reliability; or inject themselves into the logical network path between the target and the resource requested by the victim in order to read and/or modify network communications (e.g., a man in the middle attack).
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: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the impacted component are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 4 Jun 2025
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

Upgrade freshrss/FreshRSS to 1.26.2.

Affected software

Product	Affected	Fixed in
GitHubfreshrss/FreshRSS`pkg:github/freshrss/FreshRSS`Other threats	Affected <1.26.2	Fixed in 1.26.2

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

AI-suggested

Organizations should immediately upgrade all FreshRSS instances to version 1.26.2 or later, where the vulnerability is patched. Administrators must audit subscribed feeds and remove any untrusted or suspicious sources to reduce exposure. Implementing strict Content Security Policies on the FreshRSS web interface can help mitigate script injection risks. Additionally, disabling or restricting iframe sandbox attributes that allow scripts and same-origin access can limit attack vectors. Monitoring user activity for unusual behavior, especially admin accounts, is advised. Employ network-level controls to restrict outbound connections from the FreshRSS server to untrusted sources, minimizing malicious feed injection. Regularly review and harden user permissions to limit the impact of compromised accounts. Finally, educate users about the risks of subscribing to untrusted feeds and the importance of cautious interaction with feed entries.

Description

FreshRSS is a self-hosted RSS feed aggregator. Prior to version 1.26.2, it's possible to run arbitrary JavaScript on the feeds page. This occurs by combining a cross-site scripting (XSS) issue that occurs in `f.php` when SVG favicons are downloaded from an attacker-controlled feed containing `<script>` tags inside of them that aren't sanitized, with the lack of CSP in `f.php` by embedding the malicious favicon in an iframe (that has `sandbox="allow-scripts allow-same-origin"` set as its attribute). An attacker needs to control one of the feeds that the victim is subscribed to, and also must have an account on the FreshRSS instance. Other than that, the iframe payload can be embedded as one of two options. The first payload requires user interaction (the user clicking on the malicious feed entry) with default user configuration, and the second payload fires instantly right after the user adds the feed or logs into the account while the feed entry is still visible. This is because of lazy image loading functionality, which the second payload bypasses. An attacker can gain access to the victim's account by exploiting this vulnerability. If the victim is an admin it would be possible to delete all users (cause damage) or execute arbitrary code on the server by modifying the update URL using fetch() via the XSS. Version 1.26.2 has a patch for the issue.

Impact

For European organizations using FreshRSS instances, especially those self-hosting the service internally or for teams, this vulnerability poses a significant risk. An attacker controlling an RSS feed can execute arbitrary JavaScript in the context of authenticated users, leading to account compromise. For regular users, this could mean exposure of sensitive information such as feed subscriptions or personal data. For administrators, the impact escalates to potential deletion of all users or remote code execution on the server, which could lead to full system compromise, data loss, or lateral movement within the network. Given FreshRSS's role in aggregating external content, the attack surface includes any subscribed feeds, increasing the risk of supply chain style attacks. The lack of CSP and iframe sandboxing weaknesses exacerbate the threat. European organizations with compliance obligations under GDPR must consider the confidentiality breach implications and potential regulatory penalties. The medium CVSS score reflects the need for user interaction or feed control, but the severity of possible outcomes, especially for admins, is high.

Summary

CVE-2025-31136 is a cross-site scripting (XSS) vulnerability affecting FreshRSS, a popular self-hosted RSS feed aggregator, in versions prior to 1.26.2. The vulnerability arises from improper sanitization of SVG favicons downloaded from attacker-controlled RSS feeds. Specifically, the vulnerable component is the 'f.php' script, which fails to neutralize malicious <script> tags embedded inside SVG favicons. This flaw is compounded by the absence of a Content Security Policy (CSP) in 'f.php' and the use of an iframe with sandbox attributes 'allow-scripts allow-same-origin', which allows script execution within the iframe context. An attacker must control an RSS feed that the victim subscribes to and the victim must have an account on the FreshRSS instance. Two exploitation scenarios exist: one requiring user interaction (clicking the malicious feed entry) under default settings, and another that triggers immediately after feed addition or user login by leveraging lazy image loading to bypass interaction requirements. Successful exploitation enables arbitrary JavaScript execution in the victim's browser, potentially allowing account takeover. If the victim is an administrator, the attacker could delete all users or execute arbitrary server-side code by manipulating the update URL via fetch() calls through the XSS vector. The vulnerability has a CVSS 3.1 score of 6.7 (medium severity) reflecting network attack vector, high confidentiality and integrity impact, low availability impact, requiring low privileges and user interaction in one scenario. The issue was patched in FreshRSS version 1.26.2.

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

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 6 Jul 2025, 21:41 UTC

WeaknessesCWE-79

Technical details

References

Community reviews

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