When an FTP wildcard `LIST` operation fails, libcurl omits the restoration path meant for successful listings, leaving the write callback set to the internal listing parser and the write callback data pointing directly to the easy handle. Subsequent reuse of this handle triggers an immediate crash, and cloning it via `curl_easy_duphandle()` copies this corrupted state into the duplicate. If the original handle is subsequently freed, executing a transfer on the cloned handle causes a heap use-after-free read against the dangling handle reference; alternatively, reusing the original or cloned handle while changing only `CURLOPT_WRITEDATA` (and omitting `CURLOPT_WRITEFUNCTION`) results in type confusion, forcing the internal parser to interpret incoming server response bytes into memory at the application-supplied write data pointer.
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Redhat_linux | — | No solution exists | Oct 16, 2026 | Oct 14, 2026 |
| Ubuntu | — | Upgrade curlUpgrade libcurl3t64-gnutlsUpgrade libcurl3 (Ubuntu Pro)Upgrade libcurl4-gnutls-devUpgrade libcurl3-nss (Ubuntu Pro)Upgrade curl (Ubuntu Pro)Upgrade libcurl4-openssl-dev (Ubuntu Pro)Upgrade libcurl3-nssUpgrade libcurl3-gnutls (Ubuntu Pro)Upgrade libcurl4-gnutls-dev (Ubuntu Pro)Upgrade libcurl4-openssl-devUpgrade libcurl4 (Ubuntu Pro)Upgrade libcurl4-nss-devUpgrade libcurl4-nss-dev (Ubuntu Pro)Upgrade libcurl4t64Upgrade libcurl3-gnutlsUpgrade libcurl4 | Oct 14, 2026 | Oct 14, 2026 |
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