OAuth client impersonation via predictable PKCE verifier
Published Jul 22, 2026 · Updated Jul 22, 2026
Weak random generation in librest on Red Hat Enterprise Linux 10 allows remote attackers to impersonate OAuth clients via PKCE bypass. The PKCE code-verifier generator uses GLib GRand, whose predictable output lacks the cryptographic entropy required for an OAuth proof secret. Exploitation requires intercepting an authorization code and recovering the PRNG seed; a successful attacker obtains an access token that permits protected-data access and actions as the user.
Summary
What happened
Weak random generation in librest on Red Hat Enterprise Linux 10 allows remote attackers to impersonate OAuth clients via PKCE bypass. The PKCE code-verifier generator uses GLib GRand, whose predictable output lacks the cryptographic entropy required for an OAuth proof secret. Exploitation requires intercepting an authorization code and recovering the PRNG seed; a successful attacker obtains an access token that permits protected-data access and actions as the user.
The record
- CVE
- CVE-2026-16615
- Published
- Jul 22, 2026
- Updated
- Jul 22, 2026
- Vendor
- 389 Directory Server
- Product
- Red Hat Enterprise Linux 10
- Classifications
- CWE-338, T1528
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 22, 2026CVE publishedPublication date reported by the CVE source.
- Jul 22, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Affected versions are unavailable in this record. Check the vendor advisory for version and patch details.
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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