CVE-2021-27913
Use of a Broken or Risky Cryptographic Algorithm
The function mt_rand 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 This issue affects: Mautic Mautic versions prior to 3.3.4; versions prior to 4.0.0.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- Required
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- Low
Exploit likelihood
What each source reports
CVE List Score used
Use of a Broken or Risky Cryptographic Algorithm
The function mt_rand 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 This issue affects: Mautic Mautic versions prior to 3.3.4; versions prior to 4.0.0.
- Record
CVE-2021-27913- CVSS 3.1
- 3.5 Low
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:L - Weakness
- CWE-327
- Updated
- 2026-11-02
EUVDEUVD-2021-2132
The function mt_rand 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 This issue affects: Mautic Mautic versions prior to 3.3.4; versions prior to 4.0.0.
- Record
EUVD-2021-2132- CVSS 3.1
- 3.5 Low
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:L - Updated
- 2026-11-03
GitHub AdvisoriesGHSA-x7g2-wrrp-r6h3
Use of a Broken or Risky Cryptographic Algorithm
✍️ Description
The function mt_rand 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 mt_rand 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 'mt_srand(13333337); echo mt_rand( ), "\n";'
After that, copy the output (1863134308) and execute the following commands:
root$ gcc php_mt_seed.c -o php_mt_seedroot$ ./php_mt_seed 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 = 0x00cb7359 = 13333337 (PHP 7.1.0+) Hey, that's your seed!
💥 Impact
An attacker could takeover accounts at random by enumerating and using access tokens.
📝 References
- https://openwall.com/php_mt_seedhttps://crypto.di.uoa.gr/CRYPTO.SEC/Randomness_Attacks_files/paper.pdf
- https://github.com/mautic/mautic/blob/5213e320b4ef4d0c51bb84c1d46a1071e8e4f7fc/app/bundles/PointBundle/Controller/TriggerController.php#L187
- https://github.com/mautic/mautic/releases/tag/3.3.4
- https://github.com/mautic/mautic/releases/tag/4.0.0
- Record
GHSA-x7g2-wrrp-r6h3- CVSS 3.1
- 3.5 Low
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:L - Weakness
- CWE-327
- Updated
- 2026-11-02
NVD
The function mt_rand 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 This issue affects: Mautic Mautic versions prior to 3.3.4; versions prior to 4.0.0.
- Record
CVE-2021-27913- CVSS 3.1
- 3.5 Low
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:L - CVSS 3.1
- 3.5 Low
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:N/A:N - CVSS 2.0
- 3.5 Low
AV:N/AC:M/Au:S/C:P/I:N/A:N - Weakness
- CWE-327, CWE-338
- Updated
- 2026-11-02
OSV
The function mt_rand 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 This issue affects: Mautic Mautic versions prior to 3.3.4; versions prior to 4.0.0.
- Record
CVE-2021-27913- CVSS 3.1
- 3.5 Low
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:N/A:N - Updated
- 2026-11-02
OSVGHSA-x7g2-wrrp-r6h3
Use of a Broken or Risky Cryptographic Algorithm
✍️ Description
The function mt_rand 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 mt_rand 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 'mt_srand(13333337); echo mt_rand( ), "\n";'
After that, copy the output (1863134308) and execute the following commands:
root$ gcc php_mt_seed.c -o php_mt_seedroot$ ./php_mt_seed 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 = 0x00cb7359 = 13333337 (PHP 7.1.0+) Hey, that's your seed!
💥 Impact
An attacker could takeover accounts at random by enumerating and using access tokens.
📝 References
- https://openwall.com/php_mt_seedhttps://crypto.di.uoa.gr/CRYPTO.SEC/Randomness_Attacks_files/paper.pdf
- https://github.com/mautic/mautic/blob/5213e320b4ef4d0c51bb84c1d46a1071e8e4f7fc/app/bundles/PointBundle/Controller/TriggerController.php#L187
- https://github.com/mautic/mautic/releases/tag/3.3.4
- https://github.com/mautic/mautic/releases/tag/4.0.0
- Record
GHSA-x7g2-wrrp-r6h3- CVSS 3.1
- 3.5 Low
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:L - Weakness
- CWE-327
- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
mautic/corePackagist |
before 3.3.4 | 3.3.4 |
mautic/corePackagist |
4.0.0-alpha1 up to 4.0.0 | 4.0.0 |
mautic/corePackagist |
before 3.3.4, plus listed versions 1.0.01.0.0-beta1.0.0-beta21.0.0-beta31.0.0-beta4 Show 45 moreShow less1.0.0-rc11.0.0-rc21.0.0-rc31.0.0-rc41.0.11.0.21.0.31.0.41.0.51.1.01.1.11.1.21.1.31.2.01.2.0-beta11.2.11.2.21.2.31.2.41.3.01.3.11.4.01.4.12.0.02.0.12.1.02.1.12.10.02.10.0-beta2.10.12.11.02.11.0-beta2.12.02.12.0-beta2.12.12.12.1-beta2.12.22.12.2-beta2.13.02.13.0-beta2.13.12.14.02.14.0-beta2.14.12.14.1-beta |
3.3.4 |
mautic/corePackagist |
4.0.0-alpha1 up to 4.0.0, plus listed versions 4.0.0-beta4.0.0-rc |
4.0.0 |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases, published | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-27913 is a low vulnerability (CVSS 3.5) in Acquia Mautic, published August 30, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.46%, the 39th percentile. Fixed in mautic/core 3.3.4.
References
github.com/mautic/mautic/security/advisories/GHSA-x7g2-wrrp-r6h3
nvd.nist.gov/vuln/detail/CVE-2021-27913
Left out here: 66 versions. The JSON record has them.