libcurl's TFTP state machine fails to validate state transitions against the requested transfer direction, accepting opening server responses for both reads and writes interchangeably. A malicious TFTP server can respond to a download request in a way that forces the client into transmit mode, prompting libcurl to consume and transmit data from the handle's persistent `CURLOPT_READDATA` pointer - including data remaining from unrelated prior operations, such as an HTTP POST request executed on a reused handle.
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Redhat_linux | — | No solution exists | Oct 19, 2026 | Oct 14, 2026 |
| Ubuntu | — | Upgrade libcurl4Upgrade libcurl4 (Ubuntu Pro)Upgrade libcurl4-nss-dev (Ubuntu Pro)Upgrade libcurl4t64Upgrade curlUpgrade libcurl4-openssl-devUpgrade libcurl4-gnutls-dev (Ubuntu Pro)Upgrade libcurl4-nss-devUpgrade libcurl3-nssUpgrade libcurl3-nss (Ubuntu Pro)Upgrade libcurl3 (Ubuntu Pro)Upgrade libcurl4-gnutls-devUpgrade libcurl3-gnutlsUpgrade curl (Ubuntu Pro)Upgrade libcurl3-gnutls (Ubuntu Pro)Upgrade libcurl3t64-gnutlsUpgrade libcurl4-openssl-dev (Ubuntu Pro) | Oct 14, 2026 | Oct 14, 2026 |
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