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CVE-2016-2563

62
FAUCET Score

CVE-2016-2563 is a critical stack-based buffer overflow vulnerability affecting the SCP command-line utility in PuTTY before 0.67 and KiTTY 0.66.6.3 and earlier. A remote malicious server can exploit this by sending a crafted SCP-SINK file-size response during an SCP download, leading to denial of service or arbitrary code execution on the client. With a CVSS score of 9.8 (CRITICAL), this vulnerability is easily exploitable over the network with low complexity and no user interaction, potentially resulting in complete compromise of confidentiality, integrity, and availability. While not listed on the KEV catalog, an exploit (EDB-39551) is publicly available on ExploitDB, and it has garnered significant community discussion with 10 mentions, indicating awareness among security researchers.

Impacted Technologies

VendorProductVersion(s)CPE
<= 0.66.6.3CPE matchmatch criteria
cpe:2.3:a:9bis:kitty:*:*:*:*:*:*:*:*
<= 0.66CPE matchmatch criteria
cpe:2.3:a:simon_tatham:putty:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

9.8CRITICAL

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.0

Exploit Intelligence

EPSS Score
34.22%
Probability of exploitation in next 30 days
EPSS Percentile
98.2%
Percentile rank of EPSS score among Peer Group
As of 2026-07-24
Model: v2026.06.15
ExploitDB: EDB-39551 · Mar 10, 2016
This CVE's current EPSS score of 0.3422 is in the 95th percentile among its peer group of 36,829 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Vendor Patches (1)

github_advisoryvendor investigatingvia nvd_reference
View patch

References

lists.opensuse.org / opensuse-updates/2016-05/msg00131.html
seclists.org / fulldisclosure/2016/Mar/22
github.com / tintinweb/pub/tree/master/pocs/cve-2016-2563
Vendor Advisory
security.gentoo.org / glsa/201606-01
chiark.greenend.org.uk / ~sgtatham/putty/wishlist/vuln-pscp-sink-sscanf.html
Patch
securityfocus.com / bid/84296
securitytracker.com / id/1035257