CVE-2026-16615: Librest: weak random number generation in pkce implementation

Severity: medium (CVSS 6.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-07-22 · updated 2026-09-01
Weakness: CWE-338

Description

A flaw was found in librest. The PKCE implementation for OAuth authorization uses the GRand function from the GLib API, a cryptographically insecure pseudo-random number generator. Because the generated "code verifier" lacks sufficient cryptographic entropy, a malicious actor can reverse-engineer the pseudo-random number generator (PRNG) seed to predict or reconstruct the code verifier string, allowing an attacker to bypass PKCE protections and successfully impersonate the client during the OAuth 2.0 authorization flow.

Affected products

GNOME librest: all versions
Red Hat Enterprise Linux 10: all versions — fixed in 0:0.9.1-11.el10_2.1
Red Hat Enterprise Linux 10.0 Extended Update Support: all versions — fixed in 0:0.9.1-11.el10_0.1

How to fix

Upgrade to a fixed version: Red Hat Enterprise Linux 10 0:0.9.1-11.el10_2.1; Red Hat Enterprise Linux 10.0 Extended Update Support 0:0.9.1-11.el10_0.1. Check the vendor advisory for mitigations.

References

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