CVE-2026-63091

proftpd-dfsg: ProFTPD before 1.3.9c and 1.3.10rc3 contains a signed integer overflow vulnerability in the mod_sftp module's SCP siz...

CVE-2026-63091 is fixed in proftpd-dfsg on 1 platform, first by DEBIAN-CVE-2026-63091, released July 21, 2026. It is not reported as exploited. Patch Radar priority: Routine.

Routine
CVSS
n/a
No vendor severity
Exploitation
None reported
No vendor assessment
CISA KEV
Not listed
Not in the Known Exploited Vulnerabilities catalog
EPSS
0.0053
44th percentile

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.

Where it's fixed

ProductFixed inFixReleased
Linux
proftpd-dfsg · Debian 13.5 (trixie) 1.3.8.c+dfsg-4+deb13u3 DEBIAN-CVE-2026-63091 Jul 21, 2026
proftpd-dfsg · Debian 14 1.3.9c~dfsg-1 DEBIAN-CVE-2026-63091 Jul 21, 2026

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