CVE-2025-0577: 
Alma Linux vulnerability analysis and mitigation

CVE-2025-0577 is an insufficient entropy vulnerability in GNU C Library (glibc) where the vDSO getrandom acceleration may return predictable randomness. The flaw affects the getrandom and arc4random family of functions when called again after a fork() that occurred concurrently with a call to any of these functions. Affected versions include Fedora 40 glibc between glibc-2.39-28.fc40 and glibc-2.39-33.fc40 (inclusive), Fedora 41 glibc between glibc-2.40-12.fc41 and glibc-2.40-17.fc41, and CentOS 10 Stream from glibc-2.39-29.el10 to glibc-2.39-33.el10; no upstream glibc release is affected. The vulnerability was reported on January 19, 2025, and publicly disclosed on January 23, 2025. It carries a CVSS v3.1 base score of 4.8 (Medium) (Red Hat CVE, Red Hat Bugzilla).

The root cause is classified as CWE-331 (Insufficient Entropy), arising from a race condition in glibc's vDSO-accelerated getrandom implementation. When a fork() call occurs concurrently with a call to getrandom or the arc4random family, the child process may inherit a partially-initialized or duplicated random state, causing subsequent calls to these functions to produce predictable output. This issue was introduced in specific downstream (Fedora/CentOS) package versions during glibc 2.41 development and was caught before any upstream release was affected. The attack vector is network-based with high attack complexity, requiring no privileges or user interaction, but the predictability of output is the core exploitable condition (Red Hat Bugzilla, Red Hat CVE).

Successful exploitation could allow an attacker to predict values generated by getrandom or arc4random in applications running on affected systems, potentially undermining cryptographic operations, session token generation, key material derivation, or other security-critical randomness-dependent functions. The confidentiality and integrity impacts are both rated Low, with no availability impact. Applications that fork child processes and rely on these functions for security-sensitive operations — such as web servers, cryptographic daemons, or authentication services — are most at risk (Red Hat CVE, Red Hat Bugzilla).

There is no public proof-of-concept exploit and no evidence of in-the-wild exploitation as of the time of disclosure. The EPSS score is approximately 0.022% (0.000220), indicating a very low probability of exploitation in the near term. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. The high attack complexity — requiring a precise race condition between a concurrent fork() and a getrandom/arc4random call — significantly limits practical exploitability (Red Hat CVE).

Users should update glibc to a fixed version beyond the affected ranges: on Fedora 40, upgrade beyond glibc-2.39-33.fc40; on Fedora 41, upgrade beyond glibc-2.40-17.fc41; on CentOS 10 Stream, upgrade beyond glibc-2.39-33.el10. A patch was tracked via Red Hat Bugzilla bug ID 2338871. As an additional measure, applications that fork child processes and use these random functions should re-seed or reinitialize their random state after fork(). No upstream glibc release requires patching (Red Hat Bugzilla, Red Hat CVE).

The vulnerability received coverage in Linux security advisory channels, including Fedora security updates and Linux security news aggregators. A Fedora 41 glibc security advisory (FEDORA-2025-497995b101) was published addressing this and related issues. Coverage was limited to technical Linux security communities, with no significant broader media attention given the medium severity and lack of active exploitation (Linux Security).