Vulnerability · Published Oct 20, 2026 · Assigned by curl
CVE-2026-92388FTP wildcard write callback mixup
Critical 9.1
In plain English
A critical-severity use-after-free in curl from curl. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.7% (higher than 53% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.23 | curl | 8.23.0-r0 | ALPINE-CVE-2026-92388 |
| Alpine:v3.24 | curl | 8.23.0-r0 | ALPINE-CVE-2026-92388 |
| Debian:12 | curl | no fix listed | DEBIAN-CVE-2026-92388 |
| Debian:13 | curl | no fix listed | DEBIAN-CVE-2026-92388 |
| Debian:14 | curl | no fix listed | DEBIAN-CVE-2026-92388 |
| Ubuntu:22.04:LTS | curl | 7.81.0-1ubuntu1.30 | USN-8932-1 |
| Ubuntu:22.04:LTS | curl | 7.81.0-1ubuntu1.30 | UBUNTU-CVE-2026-92388 |
| Ubuntu:24.04:LTS | curl | 8.5.0-2ubuntu10.16 | USN-8932-1 |
| Ubuntu:24.04:LTS | curl | 8.5.0-2ubuntu10.16 | UBUNTU-CVE-2026-92388 |
| Ubuntu:26.04:LTS | curl | 8.18.0-1ubuntu2.8 | USN-8927-1 |
| Ubuntu:26.04:LTS | curl | 8.18.0-1ubuntu2.8 | UBUNTU-CVE-2026-92388 |
| Ubuntu:26.10 | curl | 8.20.0-2ubuntu11.1 | USN-8927-2 |
| Ubuntu:26.10 | curl | 8.20.0-2ubuntu11.1 | UBUNTU-CVE-2026-92388 |
Affected products (as reported)
Weakness: CWE-416 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H