CVE-2026-63091

MEDIUMPre-NVD 6.56.5—
EchelonGraph scoreHIGH confidence

Score 6.5 from GitHub Security Advisory (severity: HIGH) published 2026-07-20. the CNA's CVSS baseline 6.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cna:vulncheck, epss, ghsa
Trending — 4 sources updated this week
6.5
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 6.5Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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.

CVSS v3
6.5
EG Score
6.5(high)
EG Risk
29(Track)
EG Risk 29/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity65% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
21.6%
KEV
Not listed

Published

July 20, 2026

Last Modified

July 23, 2026

Advisory Details (6)

Auto-updated Jul 20, 2026
Patch available. Sources: github_commit, github_pr, github_release.
generic

ProFTPD 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-parser
github_release Patch Available

v1.3.9c

Patch available: proftpd/proftpd v1.3.9c

https://github.com/proftpd/proftpd/releases/tag/v1.3.9c
github_release Patch Available

v1.3.10rc3

Patch available: proftpd/proftpd v1.3.10rc3-3 (pre-release)

https://github.com/proftpd/proftpd/releases/tag/v1.3.10rc3-3
github_pr Patch Available

Exercise 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/2201
github_commit Patch Available

commit b9b7dde1bcd7 (proftpd/proftpd)

Patch available: proftpd/proftpd v1.3.10rc3-3 (contains commit b9b7dde1bcd7)

https://github.com/proftpd/proftpd/commit/b9b7dde1bcd74bc23366484d53856b67b8d6d95e
generic

proftpd/RELEASE_NOTES at master · proftpd/proftpd · GitHub

https://github.com/proftpd/proftpd/blob/master/RELEASE_NOTES

Vendor 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.

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 13× in last 7d / 13× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. 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. Most recent first.

  1. 2026-07-23 14:18 UTCEPSS rescore
  2. 2026-07-23 14:18 UTCEPSS rescore
  3. 2026-07-23 03:22 UTCEG score recompute
  4. 2026-07-22 23:39 UTCEG score recompute
  5. 2026-07-22 23:39 UTCGHSA enrichment
  6. 2026-07-22 14:08 UTCEPSS rescore
  7. 2026-07-22 14:08 UTCEPSS rescore
  8. 2026-07-21 15:25 UTCEPSS rescore
  9. 2026-07-21 15:25 UTCEPSS rescore
  10. 2026-07-20 16:39 UTCEG score recompute
  11. 2026-07-20 16:39 UTCGHSA enrichment
  12. 2026-07-20 14:32 UTCEG score recompute
  13. 2026-07-20 14:32 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-63091?
CVE-2026-63091 is a medium vulnerability published on July 20, 2026. ProFTPD before 1.3.9c and 1.3.10rc3 contains a signed integer overflow vulnerability in the modsftp module's SCP size-record parser that allows authenticated low-privilege attackers to bypass ASLR by sending a crafted file size value of UINT64MAX, which results in a negative offt value. Attackers…
When was CVE-2026-63091 disclosed?
CVE-2026-63091 was first published in the National Vulnerability Database on July 20, 2026, with the most recent update on July 23, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-63091 actively exploited?
CVE-2026-63091 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 21.6% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-63091?
CVE-2026-63091 has a CVSS v3 base score of 6.5 (NVD).
How do I remediate CVE-2026-63091?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-63091, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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