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
Elevated
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: 0

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

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
9.8(medium)
EG Risk
65(Track*)
EG Risk 65/100SSVC: 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
Severity98% × 45%
Exploitation40% × 40%
Automatability30% × 15%
Action: Watch closely — could escalate to Attend.
EPSS PROB
34%
EPSS %ILE
98%
KEV
Not listed

Published

April 7, 2016

Last Modified

June 17, 2026

Advisory Details (6)

Auto-updated Aug 18, 2026
🔬 Proof of concept available. No patch confirmed yet.
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
http://www.securitytracker.com/id/1035257
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

Affected Packages

(4 across 4 ecosystems)
Debian:11(1)
PackageVulnerable rangeFixed inDependents
putty—0.67-1—
Debian:12(1)
PackageVulnerable rangeFixed inDependents
putty—0.67-1—
Debian:13(1)
PackageVulnerable rangeFixed inDependents
putty—0.67-1—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
putty—0.67-1—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 5× in last 7d / 22× 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 116 total refreshes for this CVE.

  1. 2026-08-19 16:59 UTCEPSS rescore
  2. 2026-08-18 13:43 UTCEPSS rescore
  3. 2026-08-16 14:51 UTCEPSS rescore
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  8. 2026-08-10 03:39 UTCOSV refresh
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  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
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  1. 2026-07-21 15:21 UTCEPSS rescore
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  19. 2026-07-08 15:10 UTCEPSS rescore
  20. 2026-07-07 22:42 UTCOSV refresh
  21. 2026-07-07 13:42 UTCEPSS rescore
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  39. 2026-06-18 17:50 UTCEPSS rescore
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  44. 2026-06-15 17:45 UTCEPSS rescore
  45. 2026-06-14 23:14 UTCEPSS rescore
  46. 2026-06-12 23:09 UTCEPSS rescore
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  48. 2026-06-11 13:57 UTCEPSS rescore
  49. 2026-06-10 22:15 UTCEPSS rescore
  50. 2026-06-10 13:18 UTCEPSS rescore
  51. 2026-06-07 15:22 UTCEPSS rescore
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  53. 2026-06-06 13:45 UTCEPSS rescore
  54. 2026-06-05 22:44 UTCEPSS rescore
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  63. 2026-05-30 19:23 UTCOSV refresh
  64. 2026-05-29 13:41 UTCEPSS rescore
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  75. 2026-05-20 22:37 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 ↗

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 in the National Vulnerability Database 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, which ranks it in the top 1.7% of all 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?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2016-2563, 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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