CVE-2016-2563Kitty Memory Corruption
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…
Published Apr 7, 2016 · Updated Aug 4, 2026 · Also known as DEBIAN-CVE-2016-2563, UBUNTU-CVE-2016-2563
Key Facts
Patch immediately- CVE-2016-2563 is a critical-severity vulnerability (CVSS 9.8 v3) affecting Kitty (9bis), Putty (Simon Tatham).
- It is not listed in any known-exploited vulnerabilities catalog. Public exploit code is available.
- EPSS estimates a 34% probability of exploitation in the next 30 days.
- Fixed versions are available, including Kitty 0.66.6.3, Putty 0.67-1, Putty 0.67-9.1.
- Brandefense priority: patch immediately, because public exploit code exists for a high-severity flaw.
Scores
CVSS v3
9.8
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS (30-day exploit likelihood)
34%
Higher than 98.3% of all scored CVEs
Exploit maturity
Proof of concept
ATLAS score
45/100
Publication score, see How it works
Exploitation Verdict
KEV listed
Not listed
Federal due date
None
No federal due date
Ransomware use
Not reported
Attributed actors
None named
Exploit & Defence Guidance
Exploit maturity
Proof of concept
Public exploit code
1
Proof-of-concept links
In-the-wild evidence
0
Reports of active use
Advisories And Exploit References
- advisoryhttps://github.com/tintinweb/pub/tree/master/pocs/cve-2016-2563
- advisoryhttps://security-tracker.debian.org/tracker/CVE-2016-2563
- advisoryhttps://ubuntu.com/security/CVE-2016-2563
- advisoryhttps://www.cve.org/CVERecord?id=CVE-2016-2563
- advisoryhttp://tartarus.org/~simon-git/gitweb/?p=putty.git;a=commitdiff;h=bc6c15ab5f636e05b7e91883f0031a7e06117947
- patchhttp://www.chiark.greenend.org.uk/~sgtatham/putty/wishlist/vuln-pscp-sink-sscanf.html
Description
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.
Affected Products
14 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| Kitty9bis | See advisory | 0.66.6.3 |
| PuttySimon Tatham | See advisory | 0.66 |
Patched Releases
Kitty
0.66.6.3
Putty
0.67-1, 0.67-9.1, 0.66
Timeline
Publicly disclosed
Apr 7, 2016
Last updated
Aug 4, 2026
Weakness Type
- CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer
References
- advisorygithub.com · CVE-2016-2563
- advisorysecurity-tracker.debian.org · CVE-2016-2563
- advisoryubuntu.com · CVE-2016-2563
- advisorycve.org · CVERecord
- advisorytartarus.org · gitweb
FAQ
Common Questions.
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.
Affected: Kitty (9bis); Putty (Simon Tatham). The full list is in the CVE brief.
It is not listed in any known-exploited vulnerabilities catalog.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
Public exploit code is available.
Fixed versions are available, including Kitty 0.66.6.3, Putty 0.67-1, Putty 0.67-9.1.
Brandefense priority: patch immediately, because public exploit code exists for a high-severity flaw.
Is CVE-2016-2563 On Your Attack Surface?
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