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.
CVE-2026-63091
“—” beside the score: it is equal to the CVSS score beside it.
Score 6.5 from GitHub Security Advisory (severity: HIGH) published 2026-07-20. A secondary CVSS source baseline 6.5; sources differ by 0.0.
Also known asEUVD-2026-45961 (ENISA EUVD) · GHSA-gqm5-f386-9r92 (GitHub Security Advisories)Source: ENISA EUVD
- Lower severity and no public exploit yet
A fix is available — apply it.
- CVSS v3
- 6.5
- EG Score
- 6.5MEDIUMmedium confidence
- EG Risk
- 29EG Risk 29/100
EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.
How it’s computed (value × EchelonGraph’s weight)Severity65% × 45%Impact severity (EG Severity): CVSS 6.5 of 10. Never the KEV-floored or EPSS-lifted EG Score.Exploitation0.5% × 40%FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.Automatability0% × 15%CISA's SSVC Automatable value: no (Vulnrichment).SSVC (CISA's decision table, applied by EchelonGraph): Track at every mission impact level.Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.Action: A fix is available. Apply it within your standard update timelines. - EPSS PROB
- 0.5%
- EPSS %ILE
- 44th
- KEV
- Not listed
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (6.5): severity, escalated by confirmed exploitation. This CVE's 6.5 is its impact severity (EG Severity), not escalated.
- EG Severity
- 6.5 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 0.5% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-24). FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at every mission impact level.CISA BOD 26-04: 60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at every mission impact level.
A fix is available. Apply it within your standard update timelines.
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it
Published
July 20, 2026
Last Modified
July 30, 2026
Advisory Details (6)
Auto-updated Jul 20, 2026ProFTPD mod_sftp Signed Integer Overflow via SCP Size-Record Parser | Advisories | VulnCheck
https://www.vulncheck.com/advisories/proftpd-mod-sftp-signed-integer-overflow-via-scp-size-record-parserv1.3.9c
Patch available: proftpd/proftpd v1.3.9c
https://github.com/proftpd/proftpd/releases/tag/v1.3.9cv1.3.10rc3
Patch available: proftpd/proftpd v1.3.10rc3-3 (pre-release)
https://github.com/proftpd/proftpd/releases/tag/v1.3.10rc3-3Exercise caution when reading the client-provided file size for SCP u…
Patch available: proftpd/proftpd v1.3.10rc3-3 (PR #2201 merged 2026-07-01)
https://github.com/proftpd/proftpd/pull/2201commit b9b7dde1bcd7 (proftpd/proftpd)
Patch available: proftpd/proftpd v1.3.10rc3-3 (contains commit b9b7dde1bcd7)
https://github.com/proftpd/proftpd/commit/b9b7dde1bcd74bc23366484d53856b67b8d6d95eproftpd/RELEASE_NOTES at master · proftpd/proftpd · GitHub
https://github.com/proftpd/proftpd/blob/master/RELEASE_NOTESVendor Advisories for CVE-2026-63091(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Affected Packages
(4 across 4 ecosystems)
Debian:11(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| proftpd-dfsg | 1.3.7a+dfsg-12 ... 1.3.9~dfsg-5 (36 versions) |
| — |
Debian:12(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| proftpd-dfsg | 1.3.8+dfsg-4 ... 1.3.9~dfsg-5 (28 versions) |
| — |
Debian:13(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| proftpd-dfsg | 1.3.8.c+dfsg-4, 1.3.8.c+dfsg-4+deb13u1, 1.3.8.c+dfsg-4+deb13u2 |
| — |
Debian:14(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| proftpd-dfsg | 1.3.8.c+dfsg-4 ... 1.3.9~dfsg-5 (8 versions) |
| — |
Weakness Classification(2)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 10× in last 7d / 43× in last 30d)
Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.
Showing the most recent 100 of 196 refreshes on record for this CVE.
A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 96 oldest rows on record are not shown and were not checked, so the counts can still include repeats.
- 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.5% · 44th percentile
- 2026-10-26 16:32 UTCEPSS rescoreEPSS 0.5% · 44th percentile
- 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.5% · 44th percentile
- 2026-10-25 14:13 UTCEG score recompute
- 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
- 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
- 2026-10-22 19:51 UTCEG score recompute
- 2026-10-22 19:50 UTCGHSA enrichmentGHSA-gqm5-f386-9r92 · GitHub severity HIGH · GitHub CVSS 6.5
- 2026-10-22 16:35 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
- 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
- 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
- 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
- 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
- 2026-10-18 03:23 UTCEG score recompute
- 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
- 2026-10-16 16:43 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
- 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
- 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
- 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-10-12 15:49 UTCEG score recompute
- 2026-10-11 19:33 UTCEG score recompute
- 2026-10-11 16:48 UTCEG score recompute
- 2026-10-11 14:10 UTCEG score recompute
- 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
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- 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-10-04 14:57 UTCEG score recompute
- 2026-10-04 14:57 UTCGHSA enrichmentGHSA-gqm5-f386-9r92 · GitHub severity HIGH · GitHub CVSS 6.5
- 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-10-02 17:56 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-10-01 07:45 UTCEG score recompute
- 2026-10-01 07:45 UTCGHSA enrichmentGHSA-gqm5-f386-9r92 · GitHub severity HIGH · GitHub CVSS 6.5
- 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-09-28 06:23 UTCEG score recompute
- 2026-09-28 06:23 UTCGHSA enrichmentGHSA-gqm5-f386-9r92 · GitHub severity HIGH · GitHub CVSS 6.5
- 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-09-24 04:11 UTCEG score recompute
- 2026-09-24 04:11 UTCGHSA enrichmentGHSA-gqm5-f386-9r92 · GitHub severity HIGH · GitHub CVSS 6.5
- 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
- 2026-09-23 01:43 UTCEG score recompute
- 2026-09-23 01:43 UTCGHSA enrichmentGHSA-gqm5-f386-9r92 · GitHub severity HIGH · GitHub CVSS 6.5
- 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
- 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
- 2026-09-18 03:58 UTCEG score recompute
- 2026-09-18 03:58 UTCGHSA enrichmentGHSA-gqm5-f386-9r92 · GitHub severity HIGH · GitHub CVSS 6.5
- 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
- 2026-09-16 12:48 UTCEG score recompute
- 2026-09-16 12:48 UTCGHSA enrichmentGHSA-gqm5-f386-9r92 · GitHub severity HIGH · GitHub CVSS 6.5
- 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
- 2026-09-13 14:35 UTCEG score recompute
- 2026-09-13 14:35 UTCGHSA enrichmentGHSA-gqm5-f386-9r92 · GitHub severity HIGH · GitHub CVSS 6.5
- 2026-09-12 12:34 UTCEG score recompute
- 2026-09-12 12:34 UTCGHSA enrichmentGHSA-gqm5-f386-9r92 · GitHub severity HIGH · GitHub CVSS 6.5
- 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-09-11 09:37 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-09-11 09:29 UTCEG score recompute
- 2026-09-11 09:29 UTCGHSA enrichmentGHSA-gqm5-f386-9r92 · GitHub severity HIGH · GitHub CVSS 6.5
- 2026-09-09 11:58 UTCEG score recompute
- 2026-09-09 11:58 UTCGHSA enrichmentGHSA-gqm5-f386-9r92 · GitHub severity HIGH · GitHub CVSS 6.5
- 2026-09-08 22:01 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-09-07 22:56 UTCEG score recompute
- 2026-09-07 22:56 UTCGHSA enrichmentGHSA-gqm5-f386-9r92 · GitHub severity HIGH · GitHub CVSS 6.5
- 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-09-06 11:46 UTCEG score recompute
- 2026-09-06 11:46 UTCGHSA enrichmentGHSA-gqm5-f386-9r92 · GitHub severity HIGH · GitHub CVSS 6.5
- 2026-09-05 15:31 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-09-05 09:35 UTCEG score recompute
- 2026-09-05 09:35 UTCGHSA enrichmentGHSA-gqm5-f386-9r92 · GitHub severity HIGH · GitHub CVSS 6.5
- 2026-09-04 05:07 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-09-01 13:54 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-09-01 04:40 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-08-31 04:39 UTCEG score recompute
- 2026-08-31 04:39 UTCGHSA enrichmentGHSA-gqm5-f386-9r92 · GitHub severity HIGH · GitHub CVSS 6.5
- 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-08-30 02:37 UTCEG score recompute
- 2026-08-30 02:37 UTCGHSA enrichmentGHSA-gqm5-f386-9r92 · GitHub severity HIGH · GitHub CVSS 6.5
- 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-08-28 21:42 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-08-28 01:41 UTCEG score recompute
- 2026-08-28 01:41 UTCGHSA enrichmentGHSA-gqm5-f386-9r92 · GitHub severity HIGH · GitHub CVSS 6.5
- 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-08-26 23:02 UTCEG score recompute
- 2026-08-26 23:02 UTCGHSA enrichmentGHSA-gqm5-f386-9r92 · GitHub severity HIGH · GitHub CVSS 6.5
- 2026-08-26 14:46 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-08-25 21:00 UTCEG score recompute
- 2026-08-25 21:00 UTCGHSA enrichmentGHSA-gqm5-f386-9r92 · GitHub severity HIGH · GitHub CVSS 6.5
- 2026-08-25 13:49 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-08-24 18:59 UTCEG score recompute
- 2026-08-24 18:58 UTCGHSA enrichmentGHSA-gqm5-f386-9r92 · GitHub severity HIGH · GitHub CVSS 6.5
- 2026-08-23 14:58 UTCEG score recompute
Related CVEs(same product + same CWE)
Same product
10 shownDebian:11:proftpd-dfsg
- CVE-2015-3306EG 10.0 KEVEPSS p100CRITICAL
- CVE-2010-4221EG 10.0EPSS p100HIGH
- CVE-2006-5815EG 10.0EPSS p100HIGH
- CVE-2019-12815EG 9.8EPSS p99CRITICAL
- CVE-2023-48795NVD 5.9EG 9.0EPSS p100CRITICAL
- CVE-2011-4130EG 9.0EPSS p96HIGH
- CVE-2026-63090EG 8.8HIGH
- CVE-2020-9273EG 8.8EPSS p96HIGH
- CVE-2026-35025EG 8.1HIGH
- CVE-2026-44331EG 8.1HIGH
Frequently asked(5)
What is CVE-2026-63091?
When was CVE-2026-63091 made public?
Is CVE-2026-63091 actively exploited?
What is the CVSS score of CVE-2026-63091?
How do I remediate CVE-2026-63091?
Dependency Blast Radius
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