8.8

CVE-2026-63090: ProFTPD mod_sftp Heap Buffer Overflow via SFTP Packet Reassembly

Analyzed
AliasesUBUNTU-CVE-2026-63090DEBIAN-CVE-2026-63090
Published 20-07-2026Last modified 28-07-2026

Vulnerability summary

CVE-2026-63090 is a high (CVSS 8.8) Heap-based Buffer Overflow vulnerability in proftpd. EPSS estimates a 0.93% chance of exploitation in the next 30 days, higher than 60.6% of scored vulnerabilities.

Priority
Routine

Not severe (CVSS 8.7, network access); no exploitation reported by the 5 checked sources

Source freshness unavailable

How is this decided?
CVSS score
8.8/10
010
High · v3.1 (CVE.org)
EPSS score
0.93%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Timeline

  1. 20-07-2026
    PublishedVulnerability first disclosed.
  2. 28-07-2026
    Last modifiedVulnerability information updated.

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 metrics

7 scores · 4 sources · 2 versions

EPSS trend

Probability

0.93%

Chance of exploitation in the next 30 days

Percentile

61%

Versus all other CVEs

30-day change

No change 0.00 pp

From 0.93% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: network-reachable, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.

Debian1 product
  • proftpd-dfsgAll versions (No fix recorded) | < 1.3.8.c+dfsg-4+deb13u3 | < 1.3.9c~dfsg-1
Proftpd1 product
  • proftpd≥ 1.3.10rc1, < 1.3.10rc3 | < 1.3.9c | 1.3.10:rc1 | 1.3.10:rc2
Ubuntu1 product
  • proftpd-dfsgAll versions (No fix recorded)

3 vendors · 3 products

References

9 links