Quick answers
- Is CVE-2026-53994 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-53994 being exploited in the wild.
- How severe is CVE-2026-53994?
- High severity, with a CVSS score of 7.5, published 18 July 2026.
- Which products and versions are affected?
- ProFTPD Project ProFTPD < 1.3.10.
- Is there a fix for CVE-2026-53994?
- No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
- How is CVE-2026-53994 attacked?
- It is attacked over the network, in a hosted service.
- Am I affected by CVE-2026-53994?
- Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
A heap-based buffer overflow exists in the mod_sftp module of ProFTPD within the fxp_packet_read() function. The vulnerability is triggered when the function accepts an attacker-supplied 32-bit SFTP packet length of 0, leading to an unsigned integer underflow during size calculations. This results in a request for approximately 4GB of memory; however, due to an integer truncation when passing the size to the new_block() allocator as a 32-bit int, a small (~512-byte) buffer is actually allocated. Subsequent data reads then overflow this small buffer with up to 4GB of attacker-controlled data. While the primary impact is a reliable remote denial of service (crashing the session child process), heap metadata corruption may allow for more advanced exploitation. The issue is fixed in version 1.3.10.
Affected products
- ProFTPD Project ProFTPD < 1.3.10
Timeline
- 2026-07-18: disclosed
- 2026-07-18: advisory