CVE-2021-3850 is a critical-severity (CVSS 9.1) CWE-305 vulnerability in adodb/adodb-php. 1 public exploit reference exists, so weaponization risk is real. A fix is available for adodb/adodb-php — see the affected versions and patch details below.
Authentication Bypass in ADOdb/ADOdb
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2021-3850 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,636 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
adodb/adodb-php🐘adodb/adodb-phpReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
Impact
An attacker can inject values into a PostgreSQL connection string by providing a parameter surrounded by single quotes.
Depending on how the library is used in the client software, this may allow an attacker to bypass the login process, gain access to the server's IP address, etc.
Patches
The vulnerability is fixed in ADOdb versions 5.20.21 (952de6c4273d9b1e91c2b838044f8c2111150c29) and 5.21.4 or later (b4d5ce70034c5aac3a1d51d317d93c037a0938d2).
The simplest patch is to delete line 29 in drivers/adodb-postgres64.inc.php:
diff --git a/drivers/adodb-postgres64.inc.php b/drivers/adodb-postgres64.inc.php
index d04b7f67..729d7141 100644
--- a/drivers/adodb-postgres64.inc.php
+++ b/drivers/adodb-postgres64.inc.php
@@ -26,7 +26,6 @@ function adodb_addslashes($s)
{
$len = strlen($s);
if ($len == 0) return "''";
- if (strncmp($s,"'",1) === 0 && substr($s,$len-1) == "'") return $s; // already quoted
return "'".addslashes($s)."'";
}
Workarounds
Ensure the parameters passed to ADOConnection::connect() or related functions (nConnect(), pConnect()) are not surrounded by single quotes.
Credits
Thanks to Emmet Leahy (@meme-lord) of Sorcery Ltd for reporting this vulnerability, and to the huntr team for their support.
References
- Original issue report https://huntr.dev/bounties/bdf5f216-4499-4225-a737-b28bc6f5801c/
- ADOdb reference issue #793
For more information
If you have any questions or comments about this advisory:
- Add a note in issue #793
- Contact the maintainers on Gitter
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | adodb/adodb-php | all versions | 5.20.21composer require adodb/adodb-php:^5.20.21 |
| 🐘Packagist | adodb/adodb-php | ≥ 5.21.0&&< 5.21.4 | 5.21.4composer require adodb/adodb-php:^5.21.4 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for adodb/adodb-php, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update adodb/adodb-php to 5.20.21 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-3850 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2021-3850 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2021-3850. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
Frequently Asked Questions
Is CVE-2021-3850 in your dependencies?
O3 Security finds CVE-2021-3850 across Packagist dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.