# CVE-2026-16615

## Summary

- **CVE ID:** CVE-2026-16615
- **Severity:** MEDIUM
- **CVSS Score:** 6.8 (CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N)
- **CWE:** CWE-338
- **Published:** Jul 22, 2026
- **Last Modified:** Sep 1, 2026

## 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 (0)
- Red Hat — Red Hat Enterprise Linux 10 (0:0.9.1-11.el10_2.1)
- Red Hat — Red Hat Enterprise Linux 10.0 Extended Update Support (0:0.9.1-11.el10_0.1)

## References

- [CNA](https://access.redhat.com/security/cve/CVE-2026-16615)
- [CNA](https://bugzilla.redhat.com/show_bug.cgi?id=2504432)
- [CNA](https://gitlab.gnome.org/GNOME/librest/-/issues/25)
- [CNA](https://access.redhat.com/errata/RHSA-2026:47085)
- [CNA](https://access.redhat.com/errata/RHSA-2026:62222)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.25%
- **EPSS Percentile:** 16.9

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._