VulnerabilityPublished 20 Aug 2026Updated 10 Nov 2026

CVE-2026-125339: Winter · CSRF through AJAX handler names reachable as backend page actions

Affects winter/wn-backend-moduleSource GCVE Database

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Authoritative record:CVE-2026-125339· Medium 6.1

Not known to be exploited · CVSS 6.1 Medium : upgrade to 1.2.14 when convenient.

Data as of 10 Nov 2026, 22:19 UTC

CVSS 3.1 base score

6.1Medium

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

Thin evidence

One scorer or none

CVSS scores by source
CNA (GitHub_M)	CVSS 3.1	6.1

Patch: Available – fixed in 1.2.14

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

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

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: High: The attacker is authorized with (i.e., requires) privileges that provide significant (e.g., administrative) control over the vulnerable component that could affect component-wide settings and files.
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: None: There is no loss of confidentiality within the impacted component.
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: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 10 Nov 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 10 Nov 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 winter/wn-backend-module to 1.2.14.

Affected software

Product	Affected	Fixed in
Packagistwinter/wn-backend-module	Affected >=1.0.319 <1.2.14	Fixed in 1.2.14

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

Description

### Impact Affected versions of Winter CMS allow a backend AJAX handler to be invoked by a plain top-level `GET` navigation with no CSRF token. `Backend\Classes\Controller::actionExists()` accepted any public method on a controller as a page action, so handler-shaped names were never reserved from URL dispatch: an authenticated and authorized request to `/backend/system/eventlogs/index_onEmptyLog` reached the handler of the same name and truncated the system event log. Backend paths are routed through `Route::any`, and CSRF validation is skipped for `HEAD`, `GET` and `OPTIONS` requests. The default `SameSite=Lax` session cookie is sent on top-level cross-site navigation, so a link on an attacker-controlled page is sufficient — no form, no script and no token. Handler arguments are taken from URL path segments, so the attacker also chooses the target record. Affected handlers across the `backend`, `cms` and `system` modules cover log truncation, resetting settings to their defaults, altering backend user state, and deleting CMS templates. None of them disclose data to the attacker or write attacker-controlled content, so the impact is destructive and state-changing rather than confidential. To actively exploit this issue, an attacker would need no account of their own, but would need an authenticated backend user holding the relevant permission to follow an attacker-supplied link. The permissions guarding the affected handlers, `system.access_logs` included, are by default assigned only to the built-in Developer role. ### Patches Page-action dispatch is now restricted to all-lowercase method names, which reserves handler-shaped names (`onFoo`, `index_onFoo`) from being reached by URL. AJAX dispatch is unchanged: handlers continue to work over `POST` with the `X-WINTER-REQUEST-HANDLER` header exactly as before, and need no changes. >**IMPORTANT:** **This fix includes a breaking change to backend action routing.** A public controller method used as a page action must now be named in lowercase — `coming_soon()` rather than `comingSoon()` — and dashed URLs are normalised to `snake_case`, so `/coming-soon` now resolves to `coming_soon()` instead of `comingSoon()`. Plugins with a camelCase page action should rename the method and its view file to match; the published URL does not need to change. Core is unaffected, and a survey of the plugin ecosystem found the change affects only a small number of plugins. This security issue has been fixed in [v1.2.14](https://github.com/wintercms/winter/commit/353b23804dee2acf49fca996c72637040446824f). ### Workarounds If you cannot upgrade, apply https://github.com/wintercms/winter/commit/353b23804dee2acf49fca996c72637040446824f manually. As an interim mitigation, set `'same_site' => 'strict'` in `config/session.php`. A strict session cookie is not sent on cross-site top-level navigation, which prevents the victim's session accompanying an attacker's link. Review this against any single sign-on or inbound-link flows into your backend first, as it also affects legitimate cross-site entry. ### References Credit to Awwader ([@NRAwwad](https://github.com/NRAwwad)) for reporting the issue. ### For more information If you have any questions or comments about this advisory: - Email us at [hello@wintercms.com](mailto:hello@wintercms.com)

CWE-352Cross-Site Request Forgery (opens in a new tab)
Compound weaknessLikelihood of exploit: MediumCWE Top 25 (2025): #3OWASP Top 10 A01:2025: Broken Access Control (opens in a new tab)
The web application does not, or cannot, sufficiently verify whether a request was intentionally provided by the user who sent the request, which could have originated from an unauthorized actor.
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
Ensure that the application is free of cross-site scripting issues (CWE-79), because most CSRF defenses can be bypassed using attacker-controlled script.
Architecture and Design
Generate a unique nonce for each form, place the nonce into the form, and verify the nonce upon receipt of the form. Be sure that the nonce is not predictable (CWE-330).
OWASP Cheat Sheets
REST Assessment (opens in a new tab)
REST Security (opens in a new tab)
Cross-Site Request Forgery Prevention (opens in a new tab)
Authorization Testing Automation (opens in a new tab)
Insecure Direct Object Reference Prevention (opens in a new tab)
OWASP ASVS 4.0.3
V13.2.3 (opens in a new tab)
V4.2.2 (opens in a new tab)
V13.3.2 (opens in a new tab)
Attack patterns
JSON Hijacking (aka JavaScript Hijacking) (opens in a new tab)
Cross-Domain Search Timing (opens in a new tab)
Cross Site Identification (opens in a new tab)
Cross Site Request Forgery (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

WeaknessesCWE-352

Technical details

References

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