Server crash via oversized RSA public key
Published May 11, 2026 · Updated May 11, 2026
Stack buffer overflow in any1 Neat VNC before 0.9.6 allows remote attackers to crash VNC servers through an RSA-AES handshake. rsa_aes_send_challenge encrypts a client-sized challenge into a fixed 1024-byte stack buffer without limiting the supplied RSA public-key length. Pre-authentication access to a listening server using RSA-AES security type 5 or 129 is sufficient; the established consequence is a server crash.
Summary
What happened
Stack buffer overflow in any1 Neat VNC before 0.9.6 allows remote attackers to crash VNC servers through an RSA-AES handshake. rsa_aes_send_challenge encrypts a client-sized challenge into a fixed 1024-byte stack buffer without limiting the supplied RSA public-key length. Pre-authentication access to a listening server using RSA-AES security type 5 or 129 is sufficient; the established consequence is a server crash.
The record
- CVE
- CVE-2026-42859
- Published
- May 11, 2026
- Updated
- May 11, 2026
- Vendor
- any1
- Product
- Neat VNC
- Classifications
- CWE-120, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 11, 2026CVE publishedPublication date reported by the CVE source.
- May 11, 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?
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- Affected versionversion=< 0.9.6
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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