Authenticated identity spoofing via NUL-truncated PSK lookup
Published May 7, 2026 · Updated Aug 31, 2026
Authentication bypass in GnuTLS 3.6.13 through 3.8.12 allows remote authenticated users to assume another RSA-PSK identity via a NUL byte. In _gnutls_proc_rsa_psk_client_kx(), PSK lookup passes strlen(info->username) rather than the parsed username_len, truncating binary identities at the first NUL. Only TLS 1.2 servers configured for RSA-PSK are exposed; a valid PSK for the truncated identity grants the crafted identity's authorization context.
Summary
What happened
Authentication bypass in GnuTLS 3.6.13 through 3.8.12 allows remote authenticated users to assume another RSA-PSK identity via a NUL byte. In _gnutls_proc_rsa_psk_client_kx(), PSK lookup passes strlen(info->username) rather than the parsed username_len, truncating binary identities at the first NUL. Only TLS 1.2 servers configured for RSA-PSK are exposed; a valid PSK for the truncated identity grants the crafted identity's authorization context.
The record
- CVE
- CVE-2026-42010
- Published
- May 7, 2026
- Updated
- Aug 31, 2026
- Vendor
- 389 Directory Server
- Product
- Red Hat OpenShift Container Platform 4.16
- Classifications
- CWE-170, CWE-626, T1190
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- May 7, 2026CVE publishedPublication date reported by the CVE source.
- Aug 31, 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
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- RSA-PSK embedded-NUL identity proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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