Skip to main content

CVE-2021-43799

8.6
HIGHCVSS v3.1 Base Score
5.27%
LOW RiskEPSS (90th percentile)

Zulip is an open-source team collaboration tool. Zulip Server installs RabbitMQ for internal message passing. In versions of Zulip Server prior to 4.9, the initial installation (until first reboot, or restart of RabbitMQ) does not successfully limit the default ports which RabbitMQ opens; this includes port 25672, the RabbitMQ distribution port, which is used as a management port. RabbitMQ's default "cookie" which protects this port is generated using a weak PRNG, which limits the entropy of the password to at most 36 bits; in practicality, the seed for the randomizer is biased, resulting in approximately 20 bits of entropy. If other firewalls (at the OS or network level) do not protect port 25672, a remote attacker can brute-force the 20 bits of entropy in the "cookie" and leverage it for arbitrary execution of code as the rabbitmq user. They can also read all data which is sent through RabbitMQ, which includes all message traffic sent by users. Version 4.9 contains a patch for this vulnerability. As a workaround, ensure that firewalls prevent access to ports 5672 and 25672 from outside the Zulip server.

Published: 1/25/2022
Modified: 11/21/2024
Back to CVE Lookup

Vulnerability Summary

CVSS v3 Score

8.6HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N

CVSS v2 Score

5

AV:N/AC:L/Au:N/C:P/I:N/A:N

EPSS Score (Exploitation Probability)

5.27%LOW Exploitation Risk
90th percentile

This vulnerability has a 5.27% probability of being exploited in the next 30 days, ranking higher than 90% of all scored CVEs.

CWE Classification

Related Vulnerabilities

Same Weakness Type(CWE-338)

CVE-2025-67504CRITICAL 9.1

WBCE CMS is a content management system. Versions 1.6.4 and below use function GenerateRandomPassword() to create passwords using PHP's rand(). rand() is not cryptographically secure, which allows password sequences to be predicted or brute-forced. This can lead to user account compromise or privilege escalation if these passwords are used for new accounts or password resets. The vulnerability is fixed in version 1.6.5.

12/9/2025
CVE-2025-66565CRITICAL 9.8

Fiber Utils is a collection of common functions created for Fiber. In versions 2.0.0-rc.3 and below, when the system's cryptographic random number generator (crypto/rand) fails, both functions silently fall back to returning predictable UUID values, including the zero UUID "00000000-0000-0000-0000-000000000000". The vulnerability occurs through two related but distinct failure paths, both ultimately caused by crypto/rand.Read() failures, compromising the security of all Fiber applications using these functions for security-critical operations. This issue is fixed in version 2.0.0-rc.4.

12/9/2025
CVE-2024-29868CRITICAL 9.1

Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG) vulnerability in Apache StreamPipes user self-registration and password recovery mechanism. This allows an attacker to guess the recovery token in a reasonable time and thereby to take over the attacked user's account. This issue affects Apache StreamPipes: from 0.69.0 through 0.93.0. Users are recommended to upgrade to version 0.95.0, which fixes the issue.

6/24/2024
CVE-2023-36993CRITICAL 9.8

The cryptographically insecure random number generator being used in TravianZ 8.3.4 and 8.3.3 in the password reset function allows an attacker to guess the password reset.parameters and to take over accounts.

7/7/2023
CVE-2022-44796CRITICAL 9.8

An issue was discovered in Object First Ootbi BETA build 1.0.7.712. The authorization service has a flow that allows getting access to the Web UI without knowing credentials. For signing, the JWT token uses a secret key that is generated through a function that doesn't produce cryptographically strong sequences. An attacker can predict these sequences and generate a JWT token. As a result, an attacker can get access to the Web UI. This is fixed in Object First Ootbi BETA build 1.0.13.1611.

11/7/2022

Similar SeverityHIGH