Vulnerability in GNOME Librest

CVE-2026-16615

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.

EPSS: 0.003 (16.9th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 6.8 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N.

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-16615?
CVE-2026-16615 is a medium-severity vulnerability in GNOME Librest, classified under Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG). CVSS score: 6.8/10. Published 2026-07-22.
How severe is CVE-2026-16615?
Medium severity. CVSS v3 base score is 6.8 out of 10.