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CVSS estimates technical severity, but it does not automatically equal business risk. Prioritize using context like internet exposure, asset criticality, known exploitation, and whether compensating controls exist. A Medium CVSS on an exposed production system can be more urgent than a Critical on an isolated non-production host.

Vulnerability Database

Q: What is a Vulnerability (CVE) and why does it matter?

A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.

Q: What's the difference between a vulnerability, an exploit, and a zero-day?

A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. Risk increases sharply when exploitation becomes reliable or widespread.

Q: Why do vulnerabilities keep reappearing in our environment?

Recurring findings usually come from incomplete asset discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host.

Q: How do we prioritize remediation without burning out the team?

Use a repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress so remediation is steady, not reactive.

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352,262

Total vulnerabilities in the database

WWBN AVideo has Stored XSS via Unanchored Duration Regex in Video Encoder Receiver — wwbn / avideo

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Summary

The isValidDuration() regex at objects/video.php:918 uses /^[0-9]{1,2}:[0-9]{1,2}:[0-9]{1,2}/ without a $ end anchor, allowing arbitrary HTML/JavaScript to be appended after a valid duration prefix. The crafted duration is stored in the database and rendered without HTML escaping via echo Video::getCleanDuration() on trending pages, playlist pages, and video gallery thumbnails, resulting in stored cross-site scripting.

Details

Input entry point: objects/aVideoEncoderReceiveImage.json.php:208

// Line 203-211
if (!empty($_REQUEST[&#039;duration&#039;])) {
    $video-&gt;setDuration($_REQUEST[&#039;duration&#039;]);
}

Insufficient validation: objects/video.php:918

static function isValidDuration($duration) {
    // ...
    return preg_match(&#039;/^[0-9]{1,2}:[0-9]{1,2}:[0-9]{1,2}/&#039;, $duration);
    //     Missing $ anchor here -----------------------------------^
}

The regex matches 00:00:01 at the start of the string but ignores everything after it. A payload like 00:00:01</time><img src=x onerror=alert(1)><time> passes validation.

No sanitization in output function: objects/video.php:3463-3480

public static function getCleanDuration($duration = &quot;&quot;) {
    $durationParts = explode(&quot;.&quot;, $duration);
    $duration = $durationParts[0];
    $durationParts = explode(&#039;:&#039;, $duration);
    if (count($durationParts) == 1) {
        return &#039;0:00:&#039; . static::addZero($durationParts[0]);
    } elseif (count($durationParts) == 2) {
        return &#039;0:&#039; . static::addZero($durationParts[0]) . &#039;:&#039; . static::addZero($durationParts[1]);
    }
    return $duration; // Returns full string unmodified for 3+ colon parts
}

With the payload 00:00:01</time><img src=x onerror=alert(1)><time>, exploding by : yields 3+ parts, so the full unsanitized string is returned.

Unescaped output sinks:

view/trending.php:72:

&lt;time class=&quot;duration&quot;&gt;&lt;?php echo Video::getCleanDuration($value[&#039;duration&#039;]); ?&gt;&lt;/time&gt;

view/include/playlist.php:159:

&lt;time class=&quot;duration&quot;&gt;&lt;?php echo Video::getCleanDuration(@$value[&#039;duration&#039;]); ?&gt;&lt;/time&gt;

objects/video.php:7200 (gallery thumbnail generation):

$img .= &quot;&lt;time class=\&quot;duration\&quot;...&gt;&quot; . $duration . &quot;&lt;/time&gt;&quot;;

No Content-Security-Policy headers are set. The application uses raw PHP templates with no auto-escaping framework.

PoC

Authenticate as a user with upload permission and obtain a video_id_hash for a video (visible in encoder API responses or via the upload flow).
Send the malicious duration:

curl -X POST &quot;https://target/objects/aVideoEncoderReceiveImage.json.php&quot; \
  -d &quot;videos_id=VIDEO_ID&quot; \
  -d &quot;video_id_hash=HASH&quot; \
  -d &#039;duration=00:00:01&lt;/time&gt;&lt;img src=x onerror=alert(document.cookie)&gt;&lt;time&gt;&#039;

The isValidDuration() regex matches the 00:00:01 prefix and allows the full string to be stored.
Visit the trending page (/view/trending.php) or any playlist containing the poisoned video. The injected HTML breaks out of the <time> tag and the onerror handler executes JavaScript in the victim's browser context.

Impact

Session hijacking: Attacker can steal session cookies of any user (including administrators) who views a page listing the poisoned video (trending, playlists, search results, channel pages).
Account takeover: Stolen admin session cookies grant full platform control.
Phishing: Attacker can inject fake login forms or redirect users to malicious sites.
Worm potential: Since the XSS fires on commonly-visited listing pages (trending), it can propagate without targeted delivery — any visitor is a victim.

The attack requires only upload-level permissions (low privilege) and impacts all users who view any page rendering the poisoned video's duration (high blast radius).

Recommended Fix

Fix 1 — Anchor the regex (objects/video.php:918):

- return preg_match(&#039;/^[0-9]{1,2}:[0-9]{1,2}:[0-9]{1,2}/&#039;, $duration);
+ return preg_match(&#039;/^[0-9]{1,2}:[0-9]{1,2}:[0-9]{1,2}(\.[0-9]+)?$/&#039;, $duration);

Fix 2 — HTML-escape all duration output (defense in depth):

In view/trending.php:72:

- &lt;time class=&quot;duration&quot;&gt;&lt;?php echo Video::getCleanDuration($value[&#039;duration&#039;]); ?&gt;&lt;/time&gt;
+ &lt;time class=&quot;duration&quot;&gt;&lt;?php echo htmlspecialchars(Video::getCleanDuration($value[&#039;duration&#039;]), ENT_QUOTES, &#039;UTF-8&#039;); ?&gt;&lt;/time&gt;

In view/include/playlist.php:159:

- &lt;time class=&quot;duration&quot;&gt;&lt;?php echo Video::getCleanDuration(@$value[&#039;duration&#039;]); ?&gt;&lt;/time&gt;
+ &lt;time class=&quot;duration&quot;&gt;&lt;?php echo htmlspecialchars(Video::getCleanDuration(@$value[&#039;duration&#039;]), ENT_QUOTES, &#039;UTF-8&#039;); ?&gt;&lt;/time&gt;

In objects/video.php:7200:

- $img .= &quot;&lt;time class=\&quot;duration\&quot;...&gt;&quot; . $duration . &quot;&lt;/time&gt;&quot;;
+ $img .= &quot;&lt;time class=\&quot;duration\&quot;...&gt;&quot; . htmlspecialchars($duration, ENT_QUOTES, &#039;UTF-8&#039;) . &quot;&lt;/time&gt;&quot;;

Both fixes should be applied: the regex fix prevents storage of invalid data, and the output escaping provides defense in depth against any other code path that might store unvalidated durations.

Published: Apr 14, 2026
Updated: Apr 15, 2026
GHSA: GHSA-8pv3-29pp-pf8f
Severity: Medium
Exploit:
CISA KEV:

CVSS v3:

Severity: Unknown
Score:
AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

CWEs:

CWE-79

OWASP TOP 10:

A7 - Cross-Site Scripting (XSS)

Affected Software
References

Software	From	Fixed in
wwbn / avideo	-	29.0.x

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Frequently Asked Questions

What is a Vulnerability (CVE) and why does it matter?

A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.

CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.

A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. In practice, risk increases sharply when exploitation becomes reliable or widespread.

Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.

Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.

SynScan combines attack surface monitoring and continuous security auditing to keep your inventory current, flag high-impact vulnerabilities early, and help you turn raw findings into a practical remediation plan.