Buffer Over-read Affecting proftpd-dfsg package, versions <1.3.9c~dfsg-1


Severity

Recommended
0.0
medium
0
10

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Threat Intelligence

EPSS
0.53% (43rd percentile)

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  • Snyk IDSNYK-DEBIAN14-PROFTPDDFSG-18025335
  • published21 Jul 2026
  • disclosed20 Jul 2026

Introduced: 20 Jul 2026

CVE-2026-63091  (opens in a new tab)
CWE-126  (opens in a new tab)
CWE-190  (opens in a new tab)

How to fix?

Upgrade Debian:14 proftpd-dfsg to version 1.3.9c~dfsg-1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream proftpd-dfsg package and not the proftpd-dfsg package as distributed by Debian. See How to fix? for Debian:14 relevant fixed versions and status.

ProFTPD before 1.3.9c and 1.3.10rc3 contains a signed integer overflow vulnerability in the mod_sftp module's SCP size-record parser that allows authenticated low-privilege attackers to bypass ASLR by sending a crafted file size value of UINT64_MAX, which results in a negative off_t value. Attackers can exploit the subsequent conversion to uint32_t, causing an approximately 4 GB requested read length and forcing the server to read beyond the end of the SSH channel data and write overread process memory into the uploaded file. In tested configurations, the disclosed data contains libc, libcrypto, and PIE pointers sufficient to derive their randomized base addresses, thereby bypassing ASLR and enabling reliable exploitation of memory corruption vulnerabilities in the same process.

CVSS Base Scores

version 3.1