GHSA-35f3-pg38-486f YesWiki Vulnerable to Reflected XSS via Unescaped Archived-Revision `time` Parameter in `handlers/page/show.php`
SummaryYesWiki's archived-revision view reflects the `time` `GET` parameter into a hidden HTML input in `handlers/page/show.php` without escaping. Because MySQL coerces malformed `DATETIME` strings, an attacker can append HTML or JavaScript to a valid archived revision timestamp, still load that archived revision, and execute arbitrary JavaScript in the victim's browser.The vulnerable form is only rendered when the victim can both read and edit the target page. In restricted deployments this requires a victim with `read` and `write` access to that page. On a default `doryphore 4.6.5` install, public pages such as `PagePrincipale` were editable anonymously during validation, so the issue can also affect unauthenticated visitors in that configuration.DetailsThe request routing path uses the user-controlled `time` parameter to load a specific page revision. In `includes/YesWiki.php` around `Run()` line `1223`, the request is routed through:`LoadPage()` delegates to `PageManager::getOne()` in `includes/services/PageManager.php` around line `75`, which builds a SQL predicate directly from the supplied revision time:If the loaded page is an archived revision (`latest == 'N'`) and the current user has `write` access, `handlers/page/show.php` around lines `43-49` renders an edit form for that archived revision and copies `$_GET['time']` into a hidden input without `htmlspecialchars()`:That sink is reachable only when all of the following are true:The target page has at least one archived revision.The victim can `read` the target page.The victim can `write` the target page, because the archived revision edit form is rendered only inside the `if ($this->HasAccess('write'))` branch.In practice, the payload must begin with a real archived revision timestamp. A completely invalid `time` value does not reach the archived branch because YesWiki only updates the current page object when the revision lookup returns a non-empty row.During local validation on the official `doryphore 4.6.5` package, the exploit worked because MySQL accepted a malformed timestamp string as matching an existing archived revision row. For example, the following expression was coerced to the stored revision time:and the corresponding query predicate still matched the archived row:This means a payload can begin with a valid archived revision timestamp, still resolve to the archived revision, and then be reflected unescaped into the hidden HTML field.For comparison, `tools/bazar/handlers/page/show__.php` around lines `13-14` escapes the same `time` value with `htmlspecialchars()`, which shows that the core handler's behavior is inconsistent and unsafe.This issue maps to **CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')**.PoCSet up a vulnerable YesWiki instance. This was validated locally on the official `doryphore 4.6.5` release.Use a target page that has at least one archived revision. Any page with revision history is sufficient.Confirm the victim has the rights needed to reach the vulnerable sink:The victim must have `read` access to the page.The victim must have `write` access to the page.On the default validation install, these rights were available anonymously on public pages such as `PagePrincipale`, so no login was required in that configuration.Identify the timestamp of an archived revision. In the validated setup, an archived `PagePrincipale` revision existed at `2026-05-24 04:30:00`.Send the victim a crafted URL that starts with that valid archived revision timestamp and then appends an attribute-breaking payload:Open the URL in a browser as a victim who has the required `read` and `write` rights.Observe that YesWiki still loads the archived revision view and displays the archived-revision warning block, proving the malformed `time` value matched the stored archived revision.Inspect the returned HTML. The response contains the injected payload inside the hidden form field:The browser executes the injected JavaScript in the YesWiki origin. A simple payload such as `alert(1)` demonstrates code execution; a real payload could read browser-accessible data or perform actions in the victim's session.ImpactThis is a **reflected XSS** vulnerability in the archived-revision workflow.The practical access model is:The attacker only needs to send a crafted link.The victim must have `read` and `write` access to the target page.The target page must have at least one archived revision.On deployments where anonymous visitors can edit public pages, the issue can be exploited against unauthenticated visitors as well.An attacker may be able to:Execute arbitrary JavaScript in the victim's browser.Steal browser-accessible sensitive data.Perform actions as the victim inside YesWiki.Abuse the trusted YesWiki origin for phishing, UI redressing, or follow-on attacks.
CVSS v3.1 score: 6.1