CVE-2026-4115

Exploitation

Public exploit code exists. CISA's assessment records a public proof of concept. That is not a report of exploitation in the wild.

SSVC decision

• ExploitationpocPublic proof-of-concept exploit code exists. Not a report of exploitation in the wild.
• AutomatablenoAt least one step from reconnaissance to exploitation cannot be reliably automated.
• Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.

CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.

EPSS probability

0.55% probability of exploitation activity in the next 30 days.

EPSS percentile

Equal to or higher than the score of 45.9% of scored records. A rank, not a probability.

NVD base score

2.9 (CVSS v4.0), scored by the NVD independently of the CNA.

NVD CVSS vector

CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

NVD analysis status

Modified. NVD last modified this record on 2026-06-17.

Red Hat severity

No Red Hat rating. Red Hat rates the CVEs that affect its products.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

Published

2026-03-22 12:15Z7 MO AGO

Last updated

2026-05-25 01:42Z5 MO AGO

Reserved

2026-03-13

Assigning CNA

VulDB

Record state

PUBLISHED

Severity

Medium (CVSS 6.3)

CNA CVSS vector

CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P

Weaknesses

• CWE-345Insufficient Verification of Data AuthenticityClass
• CWE-347Improper Verification of Cryptographic SignatureBase

Data version

5.2

Document digest

81df5684a08014483b599db20f1235f89bf9c6b6f5f067e7f2ef18b1802fda37

• vuldb.comVDB-352429 | PuTTY Ed25519 Signature ecc-ssh.c eddsa_verify signature verificationhttps://vuldb.com/?id.352429vdb-entrytechnical-description
• vuldb.comVDB-352429 | CTI Indicators (IOB, IOC, IOA)https://vuldb.com/?ctiid.352429signaturepermissions-required
• vuldb.comSubmit #775576 | PuTTY Project (Simon Tatham) PuTTY 0.83 Improper Verification of Cryptographic Signaturehttps://vuldb.com/?submit.775576third-party-advisory
• github.comhttps://github.com/py-thok/putty-ed25519-malleability-s-plus-lrelated
• www.chiark.greenend.org.ukhttps://www.chiark.greenend.org.uk/~sgtatham/putty/wishlist/eddsa-overlarge-s.htmlrelated
• github.comhttps://github.com/py-thok/putty-ed25519-malleability-s-plus-l/blob/main/poc.pyexploit
• git.tartarus.orghttps://git.tartarus.org/?p=simon/putty.git;a=commitdiff;h=af996b5ec27ab79bae3882071b9d6acf16044549patch
• www.rfc-editor.orghttps://www.rfc-editor.org/rfc/rfc8032#section-8.4related
• www.openwall.comhttp://www.openwall.com/lists/oss-security/2026/05/24/11