CVE-2017-9091: /admin/loginc.php in Allen Disk 1.6 doesn't check if isset($_SESSION['captcha']['code']) == 1, which leads to

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HIGH 7.5REMOTEDOWNGRADE

CVE-2017-9091 is a high-severity flaw (CVSS 7.5) affecting allen disk. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

/admin/loginc.php in Allen Disk 1.6 doesn't check if isset($_SESSION['captcha']['code']) == 1, which leads to CAPTCHA bypass by emptying $_POST['captcha'].

Why this priority

High severity
Remotely exploitable, no login, no user action

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.3% (top 29%)
CISA exploited list	No
Weakness	CWE-20
Published	2017-05-19
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: allen disk project

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2017-05-19 18:29 UTCPublished CVE record published
2026-06-17 01:27 UTCUpdated Record last modified

allen disk project allen disk DOWNGRADE

Affected: 1.6

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.6

1. Check installed version

apt-cache policy allen-disk || rpm -q allen-disk || allen-disk --version

2. No fixed release: DOWNGRADE to a release before 1.6 (Debian / Ubuntu)

apt-cache madison allen-disk sudo apt install allen-disk=<VERSION_BEFORE_1.6> sudo apt-mark hold allen-disk

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list allen-disk sudo dnf downgrade allen-disk-<VERSION_BEFORE_1.6> sudo dnf versionlock add allen-disk

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2017-9091?

allen disk: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2017-9091 being exploited?

CVE-2017-9091 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2017-9091 affect?

CVE-2017-9091 affects allen disk. Severity is high (CVSS 7.5). /admin/loginc.php in Allen Disk 1.6 doesn't check if isset($_SESSION['captcha']['code']) == 1, which leads to CAPTCHA bypass by emptying $_POST['captcha'].

How urgent is CVE-2017-9091?

Priority 49/100. High severity; Remotely exploitable, no login, no user action

Software pages

PHP vulnerabilities

Related CVEs

CVE-2017-9307 MEDIUM 6.5 DOWNGRADE SSRF vulnerability in remotedownload.php in Allen Disk 1.6 allows remote authenticated users to conduct port s
CVE-2017-9249 MEDIUM 5.4 DOWNGRADE Cross-site scripting (XSS) vulnerability in Allen Disk 1.6 allows remote authenticated users to inject arbitra
CVE-2017-9090 HIGH 7.5 DOWNGRADE reg.php in Allen Disk 1.6 doesn't check if isset($_SESSION['captcha']['code'])==1, which makes it possible to
CVE-2017-8848 MEDIUM 6.5 DOWNGRADE Allen Disk 1.6 has CSRF in setpass.php with an impact of changing a password.
CVE-2017-8832 MEDIUM 6.1 DOWNGRADE Allen Disk 1.6 has XSS in the id parameter to downfile.php.

References

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