CVE-2026-63091
Last modified
CVE-2026-63091 is a high-severity vulnerability rated 7.1/10 on the CVSS scale. 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. EPSS estimates a 0.29% chance of exploitation in the next 30 days.
Description
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.
Metrics
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Weakness Enumeration
Affected Software
Source: CNA advisory (CVE.org). NVD analysis pending.
| Vendor | Product | Versions |
|---|---|---|
| proftpd | proftpd | < 1.3.9c; >= 1.3.10rc1, < 1.3.10rc3 |
References
Timeline
- Published
- Last Modified
- Status
- Awaiting Analysis
Frequently Asked Questions
What is CVE-2026-63091?
How severe is CVE-2026-63091?
How do I fix CVE-2026-63091?
How Strix Helps
- How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
- Autonomous PentestingAI agents that find and validate exploitable vulnerabilities like this one across your applications.
- PR ReviewsPentest every pull request so vulnerable code is caught before it ships to production.
- AI Penetration TestingHow AI-driven penetration testing continuously covers your attack surface.
Related CVEs from 2026
- CVE-2026-63086text-generation-inference through 3.3.7 contains a server-si…8.6
- CVE-2026-63087Grafana OnCall through 1.16.11 contains an unauthenticated a…9.8
- CVE-2026-63088stoatchat before 0.14.0 contains a server-side request forge…8.6
- CVE-2026-63089WireGuard Easy through 15.3.0, fixed in commit 66b292b, cont…9.3
- CVE-2026-6309Use after free in Viz in Google Chrome prior to 147.0.7727.1…8.3
- CVE-2026-63090ProFTPD before 1.3.9c and 1.3.10rc3 contains a heap-based bu…8.8
- CVE-2026-63092kirby-modules through 5.5.7, fixed in commit 315417e, contai…5.3
- CVE-2026-63093Cursor for Windows version 3.2.16 contains a binary planting…8.8
- CVE-2026-63094SigNoz before 0.134.0 contains an open redirect vulnerabilit…8.1
- CVE-2026-63095Dendrite through 0.13.8 contains an improper authorization v…7.1
- CVE-2026-63096Dendrite through 0.13.8 contains a server-side request forge…6.9
- CVE-2026-63097Dendrite through 0.13.8 contains an improper access control …5.3
Are you affected by CVE-2026-63091?
Run a free Strix scan to check your systems for this vulnerability.
Scan your code nowSource: NVD / NIST