Low severity · published Mar 22, 2026
CVE-2026-4115
PuTTY Ed25519 Signature ecc-ssh.c eddsa_verify signature verification
3.7
CVSS
0.6%
EPSS
No
On KEV
Description
A vulnerability was detected in PuTTY 0.83. Affected is the function eddsa_verify of the file crypto/ecc-ssh.c of the component Ed25519 Signature Handler. The manipulation results in improper verification of cryptographic signature. The attack may be performed from remote. The attack requires a high level of complexity. The exploitability is told to be difficult. The exploit is now public and may be used. The real existence of this vulnerability is still doubted at the moment. The patch is identified as af996b5ec27ab79bae3882071b9d6acf16044549. It is advisable to implement a patch to correct this issue. The vendor was contacted early, responded in a very professional manner and quickly released a patch for the affected product. However, at the moment there is no proof that this flaw might have any real-world impact.
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
Attack vector
Network
Complexity
High
Privileges
None
User interaction
None
Confidentiality
None
Integrity
Low
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.6% · higher than 46% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
PU
PuTTY · Putty
0.83 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-4115
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-4115
Permissions Required
https://git.tartarus.org/?p=simon/putty.git;a=commitdiff;h=af996b5ec27ab79bae3882071b9d6acf16044549
Third Party Advisory
https://github.com/py-thok/putty-ed25519-malleability-s-plus-l
Exploit
https://github.com/py-thok/putty-ed25519-malleability-s-plus-l/blob/main/poc.py
Permissions Required
https://vuldb.com/?ctiid.352429
Third Party Advisory
https://vuldb.com/?id.352429
Third Party Advisory
https://vuldb.com/?submit.775576
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