CVE-2026-63091

MEDIUMPre-NVD 6.56.5—
EchelonGraph scoreMEDIUM confidence

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.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 3 sources updated this week
6.5EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 6.5Exploit: None knownExposed: 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(medium)
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%
Exploitation1% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
43%
KEV
Not listed

Published

July 20, 2026

Last Modified

July 30, 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.

Affected Packages

(4 across 4 ecosystems)
Debian:11(1)
PackageVulnerable rangeFixed inDependents
proftpd-dfsg1.3.7a+dfsg-12 ... 1.3.9~dfsg-5 (36 versions)——
Debian:12(1)
PackageVulnerable rangeFixed inDependents
proftpd-dfsg1.3.8+dfsg-4 ... 1.3.9~dfsg-5 (28 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
proftpd-dfsg1.3.8.c+dfsg-4 ... 1.3.9~dfsg-5 (12 versions)——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
proftpd-dfsg1.3.8.c+dfsg-4 ... 1.3.9~dfsg-5 (8 versions)1.3.9c~dfsg-1—

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 16× in last 7d / 66× 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.

Showing the most recent 100 of 135 total refreshes for this CVE.

  1. 2026-09-11 14:53 UTCEPSS rescore
  2. 2026-09-11 09:37 UTCEPSS rescore
  3. 2026-09-11 09:29 UTCEG score recompute
  4. 2026-09-11 09:29 UTCGHSA enrichment
  5. 2026-09-09 11:58 UTCEG score recompute
  6. 2026-09-09 11:58 UTCGHSA enrichment
  7. 2026-09-08 22:01 UTCEPSS rescore
  8. 2026-09-07 22:56 UTCEG score recompute
  9. 2026-09-07 22:56 UTCGHSA enrichment
  10. 2026-09-07 16:01 UTCEPSS rescore
  11. 2026-09-06 13:47 UTCEPSS rescore
  12. 2026-09-06 11:46 UTCEG score recompute
  13. 2026-09-06 11:46 UTCGHSA enrichment
  14. 2026-09-05 15:31 UTCEPSS rescore
  15. 2026-09-05 09:35 UTCEG score recompute
  16. 2026-09-05 09:35 UTCGHSA enrichment
  17. 2026-09-04 05:07 UTCEPSS rescore
  18. 2026-09-02 14:12 UTCEPSS rescore
  19. 2026-09-01 13:54 UTCEPSS rescore
  20. 2026-09-01 04:40 UTCEPSS rescore
  21. 2026-08-31 04:39 UTCEG score recompute
  22. 2026-08-31 04:39 UTCGHSA enrichment
  23. 2026-08-30 19:17 UTCEPSS rescore
  24. 2026-08-30 02:37 UTCEG score recompute
  25. 2026-08-30 02:37 UTCGHSA enrichment
Show 75 more
  1. 2026-08-30 01:22 UTCEPSS rescore
  2. 2026-08-28 21:42 UTCEPSS rescore
  3. 2026-08-28 01:41 UTCEG score recompute
  4. 2026-08-28 01:41 UTCGHSA enrichment
  5. 2026-08-27 14:25 UTCEPSS rescore
  6. 2026-08-26 23:02 UTCEG score recompute
  7. 2026-08-26 23:02 UTCGHSA enrichment
  8. 2026-08-26 14:46 UTCEPSS rescore
  9. 2026-08-25 21:00 UTCEG score recompute
  10. 2026-08-25 21:00 UTCGHSA enrichment
  11. 2026-08-25 13:49 UTCEPSS rescore
  12. 2026-08-24 18:59 UTCEG score recompute
  13. 2026-08-24 18:58 UTCGHSA enrichment
  14. 2026-08-23 14:58 UTCEG score recompute
  15. 2026-08-23 14:58 UTCGHSA enrichment
  16. 2026-08-23 00:19 UTCEPSS rescore
  17. 2026-08-22 12:57 UTCEG score recompute
  18. 2026-08-22 12:57 UTCGHSA enrichment
  19. 2026-08-21 23:49 UTCEPSS rescore
  20. 2026-08-21 10:54 UTCEG score recompute
  21. 2026-08-21 10:54 UTCGHSA enrichment
  22. 2026-08-20 22:55 UTCEPSS rescore
  23. 2026-08-20 08:51 UTCEG score recompute
  24. 2026-08-20 08:51 UTCGHSA enrichment
  25. 2026-08-19 17:04 UTCEPSS rescore
  26. 2026-08-19 06:50 UTCEG score recompute
  27. 2026-08-19 06:50 UTCGHSA enrichment
  28. 2026-08-18 13:48 UTCEPSS rescore
  29. 2026-08-18 04:23 UTCEG score recompute
  30. 2026-08-18 04:23 UTCGHSA enrichment
  31. 2026-08-17 13:47 UTCEPSS rescore
  32. 2026-08-17 02:09 UTCEG score recompute
  33. 2026-08-17 02:09 UTCGHSA enrichment
  34. 2026-08-16 14:56 UTCEPSS rescore
  35. 2026-08-16 00:08 UTCEG score recompute
  36. 2026-08-16 00:08 UTCGHSA enrichment
  37. 2026-08-15 01:30 UTCEPSS rescore
  38. 2026-08-14 22:06 UTCEG score recompute
  39. 2026-08-14 22:06 UTCGHSA enrichment
  40. 2026-08-13 22:00 UTCEPSS rescore
  41. 2026-08-13 20:05 UTCGHSA enrichment
  42. 2026-08-12 18:04 UTCEG score recompute
  43. 2026-08-12 18:04 UTCGHSA enrichment
  44. 2026-08-12 13:51 UTCEPSS rescore
  45. 2026-08-11 16:02 UTCEG score recompute
  46. 2026-08-11 16:02 UTCGHSA enrichment
  47. 2026-08-11 00:00 UTCEPSS rescore
  48. 2026-08-10 14:01 UTCEG score recompute
  49. 2026-08-10 14:01 UTCGHSA enrichment
  50. 2026-08-09 13:47 UTCEPSS rescore
  51. 2026-08-09 12:00 UTCEG score recompute
  52. 2026-08-09 12:00 UTCGHSA enrichment
  53. 2026-08-08 16:37 UTCEPSS rescore
  54. 2026-08-08 09:58 UTCEG score recompute
  55. 2026-08-08 09:58 UTCGHSA enrichment
  56. 2026-08-07 07:57 UTCEG score recompute
  57. 2026-08-07 07:57 UTCGHSA enrichment
  58. 2026-08-06 13:47 UTCEPSS rescore
  59. 2026-08-06 05:56 UTCEG score recompute
  60. 2026-08-06 05:56 UTCGHSA enrichment
  61. 2026-08-05 19:17 UTCEPSS rescore
  62. 2026-08-05 19:17 UTCEPSS rescore
  63. 2026-08-05 03:55 UTCEG score recompute
  64. 2026-08-05 03:55 UTCGHSA enrichment
  65. 2026-08-04 15:10 UTCEPSS rescore
  66. 2026-08-04 10:39 UTCEPSS rescore
  67. 2026-08-04 01:54 UTCGHSA enrichment
  68. 2026-08-02 23:53 UTCEG score recompute
  69. 2026-08-02 23:53 UTCGHSA enrichment
  70. 2026-08-02 02:27 UTCEPSS rescore
  71. 2026-08-01 21:52 UTCEG score recompute
  72. 2026-08-01 21:52 UTCGHSA enrichment
  73. 2026-08-01 04:16 UTCEPSS rescore
  74. 2026-07-31 19:51 UTCGHSA enrichment
  75. 2026-07-30 17:28 UTCEG score recompute

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 30, 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 1% probability of exploitation in the next 30 days, which ranks it in the top 57.1% of all scored CVEs.
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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