# CVE-2025-7394: In the OpenSSL compatibility layer implementation, the function RAND_poll() was not behaving as expected and leading to the potential for predictable values returned from RAND_bytes() after fork() is called. This can lead to weak or predictable random numbers generated in applications that are both using RAND_bytes() and doing fork() operations. This only affects applications explicitly calling RAND_bytes() after fork() and does not affect any internal TLS operations. Although RAND_bytes() documentation in OpenSSL calls out not being safe for use with fork() without first calling RAND_poll(), an additional code change was also made in wolfSSL to make RAND_bytes() behave similar to OpenSSL after a fork() call without calling RAND_poll(). Now the Hash-DRBG used gets reseeded after detecting running in a new process. If making use of RAND_bytes() and calling fork() we recommend updating to the latest version of wolfSSL. Thanks to Per Allansson from Appgate for the report.

CVE-2025-7394 is fixed in wolfssl on 1 platform, first by DEBIAN-CVE-2025-7394, released July 18, 2025. It is not reported as exploited. Patch Radar priority: Urgent.

- Web page: https://patchblox.com/security/cve/CVE-2025-7394
- Priority: Urgent
- CVSS: 9.8 (critical)
- EPSS: 0.0046
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jul 18, 2025
- Weakness: Exposure of Sensitive Information to an Unauthorized Actor
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-7394

## Description

In the OpenSSL compatibility layer implementation, the function RAND_poll() was not behaving as expected and leading to the potential for predictable values returned from RAND_bytes() after fork() is called. This can lead to weak or predictable random numbers generated in applications that are both using RAND_bytes() and doing fork() operations. This only affects applications explicitly calling RAND_bytes() after fork() and does not affect any internal TLS operations. Although RAND_bytes() documentation in OpenSSL calls out not being safe for use with fork() without first calling RAND_poll(), an additional code change was also made in wolfSSL to make RAND_bytes() behave similar to OpenSSL after a fork() call without calling RAND_poll(). Now the Hash-DRBG used gets reseeded after detecting running in a new process. If making use of RAND_bytes() and calling fork() we recommend updating to the latest version of wolfSSL. Thanks to Per Allansson from Appgate for the report.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | wolfssl Debian 12.15 (bookworm) | 5.5.4-2+deb12u2 | [DEBIAN-CVE-2025-7394](https://patchblox.com/security/data/fix/linux/debian-cve-2025-7394.md) | Jul 18, 2025 |
| Linux | wolfssl Debian 13.5 (trixie) | 5.7.2-0.1+deb13u1 | [DEBIAN-CVE-2025-7394](https://patchblox.com/security/data/fix/linux/debian-cve-2025-7394.md) | Jul 18, 2025 |

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