CVE-2016-2563

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2022-05-17. NVD baseline CVSS 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Trending — 3 sources updated this weekElevated
9.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 34%CVSS: 9.8Exploit: Elevated riskExposed services: Not assessed

A fix is available — apply it.

Stack-based buffer overflow in the SCP command-line utility in PuTTY before 0.67 and KiTTY 0.66.6.3 and earlier allows remote servers to cause a denial of service (stack memory corruption) or execute arbitrary code via a crafted SCP-SINK file-size response to an SCP download request.

CVSS v3
9.8
EG Score
9.8CRITICALmedium confidence
EG Risk
65
EG Risk 65/100CISA SSVC

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
Severity98% × 45%
Exploitation40% × 40%
Automatability30% × 15%
CISA SSVC: Track at low, Track* at medium and Attend at high mission impact.
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
34%
EPSS %ILE
98th
KEV
Not listed

CISA SSVCTrack at low, Track* at medium and Attend at high mission impact.

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation public PoC (EG-KEV: elevated) · Automatable unknown (not published for this CVE) · Technical impact total (CVSS ≥ 9.0). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

April 7, 2016

Last Modified

June 17, 2026

Advisory Details (6)

Auto-updated Sep 30, 2026
🔬 Proof of concept available. Patch available.
generic🟡 PoC Available

Full Disclosure: CVE-2016-2563 - PuTTY/PSCP <=0.66 buffer overflow - vuln-pscp-sink-sscanf

http://seclists.org/fulldisclosure/2016/Mar/22
generic

PuTTY: Multiple vulnerabilities (GLSA 201606-01) — Gentoo security

https://security.gentoo.org/glsa/201606-01
generic🟡 PoC Available

pub/pocs/cve-2016-2563 at master · tintinweb/pub · GitHub

https://github.com/tintinweb/pub/tree/master/pocs/cve-2016-2563
generic

CVE-2016-2563 - PSIRT.COM

http://www.securityfocus.com/bid/84296
generic

PuTTY vulnerability vuln-pscp-sink-sscanf

http://www.chiark.greenend.org.uk/~sgtatham/putty/wishlist/vuln-pscp-sink-sscanf.html
generic
http://www.securitytracker.com/id/1035257

Affected Packages

(4 across 4 ecosystems)
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
putty—
  • every version up to 0.67-1: fixed in 0.67-1
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
putty—
  • every version up to 0.67-1: fixed in 0.67-1
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
putty—
  • every version up to 0.67-1: fixed in 0.67-1
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
putty—
  • every version up to 0.67-1: fixed in 0.67-1
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 6× in last 7d / 18× 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 141 total refreshes for this CVE.

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

Publicly available exploits

(1 reference)

Working exploit code is in the public domain (1 Exploit-DB entry). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • Exploit-DBEDB-39551
    First seen Mar 10, 2016

    Putty pscp 0.66 - Stack Buffer Overwrite

    Open source ↗

Related CVEs(same product + same CWE)

Frequently asked(5)

What is CVE-2016-2563?
CVE-2016-2563 is a critical vulnerability published on April 7, 2016. Stack-based buffer overflow in the SCP command-line utility in PuTTY before 0.67 and KiTTY 0.66.6.3 and earlier allows remote servers to cause a denial of service (stack memory corruption) or execute arbitrary code via a crafted SCP-SINK file-size response to an SCP download request.
When was CVE-2016-2563 disclosed?
CVE-2016-2563 was first published on April 7, 2016, with the most recent update on June 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2016-2563 actively exploited?
CVE-2016-2563 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 34% probability of exploitation in the next 30 days (98th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2016-2563?
CVE-2016-2563 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2016-2563?
A fix for CVE-2016-2563 is available: update to the fixed version the vendor names in its advisory.

Dependency Blast Radius

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