Use of a Broken or Risky Cryptographic Algorithm

Exploitation

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

CVSS

3.5 · CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:L

EPSS

• CVE-2021-27913: 0.46% estimated exploitation activity in the next 30 days; percentile 39.78 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

✍️ Description The function mtrand is used to generate session tokens, this function is cryptographically flawed due to its nature being one pseudorandomness, an attacker can take advantage of the cryptographically insecure nature of this function to enumerate session tokens for accounts that are not under his/her control 🕵️‍♂️ Proof of Concept Numerous examples and attack implementations can be found in this paper . If you're looking for a practical tool that can crack your mtrand implementation's seed value, see this project and run the following commands in a console with php5 and OpenWall's tool installed: root$ php -r 'mtsrand(13333337); echo mtrand( ), "\n";' After that, copy the output (1863134308) and execute the following commands: root$ gcc phpmtseed.c -o phpmtseedroot$ ./phpmtseed 1863134308 After waiting ~1 minute you should have a few possible seeds corresponding to their PHP versions, next to your installed PHP version you should see something akin to: seed =…

Published by the source

1 Sep 2021, 18:41 UTC

Last modified by the source

5 Feb 2024, 15:50 UTC

Source last checked

26 Oct 2026, 14:15 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-x7g2-wrrp-r6h3

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# Patch Next advisory brief: CVE-2021-27913

Advisory: Use of a Broken or Risky Cryptographic Algorithm
IDs: CVE-2021-27913, GHSA-x7g2-wrrp-r6h3
Record: https://patchnext.com/advisories/cve-2021-27913 (revision 1, source checked 26 Oct 2026, 14:15 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Low (CVSS 3.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: mautic/core 4.0.0, 3.3.4. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist mautic/core: affected < 3.3.4; >= 4.0.0-alpha1, < 4.0.0; fixed in 4.0.0, 3.3.4

## Suggested inspection (read-only)
- Packagist mautic/core: 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 mautic/core.
- 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-x7g2-wrrp-r6h3 (GitHub-reviewed advisory GHSA-x7g2-wrrp-r6h3 lists affected ranges: Packagist mautic/core >=0 =4.0.0-alpha1 <4.0.0)

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