spomky-labs/otphp: Unbounded digits parameter in a provisioning URI triggers an uncaught DivisionByZeroError in OTP generation

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

8.7 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N · score source

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

Summary The digits parameter parsed from a provisioning URI is validated only with a lower bound ($value 0) and has no upper bound (src/OTP.php:353-357). OTP generation computes $code % (10 $this-getDigits()) (src/OTP.php:283). When digits is large enough that 10 digits overflows PHP's integer range and the (int) cast yields 0 (around digits = 40 on 64-bit PHP 8.x), the modulo operand becomes 0 and PHP raises a DivisionByZeroError. Impact OTPHP\Factory::loadFromProvisioningUri() forwards the attacker-controlled digits query value to setParameter('digits', $value), so a hostile URI such as otpauth://totp/Alice?secret=JBSWY3DPEHPK3PXP&digits=50 produces an OTP object whose at(), now(), and verify() all throw DivisionByZeroError. Because DivisionByZeroError extends Error (not Exception), callers that guard OTP generation with a catch (\Exception) do not catch it, turning a malformed URI into an unhandled fatal error (denial of service of the verification path). Measured threshold on PHP…

Published by the source

18 Jun 2026, 20:45 UTC

Last modified by the source

18 Jun 2026, 20:45 UTC

Source last checked

26 Oct 2026, 14:49 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-g7m4-839x-ch6v

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# Patch Next advisory brief: GHSA-g7m4-839x-ch6v

Advisory: spomky-labs/otphp: Unbounded digits parameter in a provisioning URI triggers an uncaught DivisionByZeroError in OTP generation
IDs: GHSA-g7m4-839x-ch6v
Record: https://patchnext.com/advisories/ghsa-g7m4-839x-ch6v (revision 1, source checked 26 Oct 2026, 14:49 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: spomky-labs/otphp 11.4.3. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist spomky-labs/otphp: affected < 11.4.3; fixed in 11.4.3

## Suggested inspection (read-only)
- Packagist spomky-labs/otphp: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on spomky-labs/otphp.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-g7m4-839x-ch6v (GitHub-reviewed advisory GHSA-g7m4-839x-ch6v lists affected ranges: Packagist spomky-labs/otphp >=0 <11.4.3)

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