CVE-2026-63090
CVE-2026-63090 — ProFTPD mod_sftp Heap Buffer Overflow via SFTP Packet Reassembly
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.
Published Updated Sources: cvelistV5, VulnCheck
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the scoring sources call it.
Exploitation
Unreported
no source claims exploitation
EPSS
1%
chance of exploitation in 30 days
CVSS base
8.8
HIGH
CISA SSVC assessment
Three decision points CISA publishes for the CVEs it assesses · SSVC 2.0.3. A stakeholder decision, not a severity score.
Exploitation
None
none · proof-of-concept · active
Automatable
No
can an attacker script all four kill-chain steps
Technical impact
Total
partial · total control of the vulnerable component
Affected scope
The catalog records vendors and products as separate lists, not pairs, so which product belongs to which vendor is not something this page can say.
Vendors (1)
Products (1)
Every base score collected
Sources score independently and disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Source |
|---|---|---|---|---|---|
| 8.8 | CVSS 3.1 | HIGH | — | — | cvelistV5 |
Weakness & attack patterns
- CWE-122
References
6 on the record
- github.com/proftpd/proftpd/blob/master/RELEASE_NOTES
release-notes
- github.com/proftpd/proftpd/releases/tag/v1.3.10rc3-3
patch, release-notes
- github.com/proftpd/proftpd/releases/tag/v1.3.9c
patch, release-notes
- github.com/proftpd/proftpd/issues/2190
issue-tracking
- github.com/proftpd/proftpd/commit/4ee8701bcf425f11b3b2116e634ff3e655d918b1
patch
- www.vulncheck.com/advisories/proftpd-mod-sftp-heap-buffer-overflow-via-sftp-packet-reassembly
third-party-advisory
Elsewhere on this site
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.