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Vulnerability record · CVE-2026-63090 · published 20 July 2026

CVE-2026-63090: Proftpd heap-based buffer overflow vulnerability

PProftpd · Proftpd

ProFTPD before 1.3.9c and 1.3.10rc3 contains a heap-based buffer overflow vulnerability in the mod_sftp module that allows authenticated low-privilege attackers to achieve arbitrary code execution by sending crafted SFTP packet fragments exceeding the 16 KB reassembly buffer in the fxp.c component. Attackers can supply oversized fragments to trigger an incorrectly conditioned reallocation, corrupt pool freelist metadata, overwrite the root_fs BSS global pointer to reference a fake filesystem struct, and redirect pr_fsio_stat() to system() via a crafted RENAME request.

8.7 CVSS 4.0 High EPSS 0.93% · top 41.0% CWE-122 · Heap-based buffer overflow
8.7CVSS 4.0 base score
0.93%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
6References
30 Jul 2026Last modified by NVD

Description

ProFTPD before 1.3.9c and 1.3.10rc3 contains a heap-based buffer overflow vulnerability in the mod_sftp module that allows authenticated low-privilege attackers to achieve arbitrary code execution by sending crafted SFTP packet fragments exceeding the 16 KB reassembly buffer in the fxp.c component. Attackers can supply oversized fragments to trigger an incorrectly conditioned reallocation, corrupt pool freelist metadata, overwrite the root_fs BSS global pointer to reference a fake filesystem struct, and redirect pr_fsio_stat() to system() via a crafted RENAME request.

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/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:

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/proftpd/proftpd/blob/master/RELEASE_NOTES Release Notes
https://github.com/proftpd/proftpd/commit/4ee8701bcf425f11b3b2116e634ff3e655d918b1 Patch
https://github.com/proftpd/proftpd/issues/2190 Issue Tracking
https://github.com/proftpd/proftpd/releases/tag/v1.3.10rc3-3 ProductRelease Notes
https://github.com/proftpd/proftpd/releases/tag/v1.3.9c ProductRelease Notes
https://www.vulncheck.com/advisories/proftpd-mod-sftp-heap-buffer-overflow-via-sftp-packet-reassembly Third Party AdvisoryPatchRelease Notes

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-63090), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.