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.
Published: 2026-03-22
Score: 6.3 Medium
EPSS: < 1% Very Low
KEV: No
Impact: Improper verification of Ed25519 signatures
Action: Apply Patch
AI Analysis

Impact

PuTTY’s Ed25519 signature handler contains a flaw that allows the eddsa_verify function to accept malformed or tampered signatures as authentic. This undermines the integrity of authentication procedures that rely on Ed25519, potentially enabling an attacker to impersonate a legitimate user or tamper with authenticated data. The weakness is rooted in improper signature validation, aligning with CWE‑345 and CWE‑347.

Affected Systems

PuTTY version 0.83 is affected. The flaw is present in the crypto/ecc-ssh.c component and was addressed by commit af996b5ec27ab79bae3882071b9d6acf16044549, which is included in later releases. Systems running the vulnerable version without this patch remain exposed to the risk described.

Risk and Exploitability

The CVSS score of 6.3 indicates moderate severity, and while the publicly available exploit exists, its manual description states high complexity and difficulty, with no current evidence of real‑world usage. The exploit can be launched remotely, but EPSS data is unavailable and the vulnerability is not listed in the CISA KEV catalog, suggesting limited large‑scale activity. Administrators should still consider the risk, particularly if PuTTY is used for critical authentication, and prioritize applying the patch promptly.

Generated by OpenCVE AI on March 22, 2026 at 13:50 UTC.

Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

  • Update PuTTY to the latest version that incorporates the eddsa_verify fix, or apply the patch provided by commit af996b5ec27ab79bae3882071b9d6acf16044549.
  • Verify the integrity of the updated binary using the supplied checksum or digital signature.
  • Audit active SSH sessions for any suspicious activity that may have occurred while the vulnerable version was in use.
  • Keep monitoring vendor advisories for additional details on potential exploitation or persistence techniques.

Generated by OpenCVE AI on March 22, 2026 at 13:50 UTC.

Tracking

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Advisories

No advisories yet.

History

Mon, 23 Mar 2026 16:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Sun, 22 Mar 2026 12:45:00 +0000

Type Values Removed Values Added
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 弱身份验证. 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. 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.
Title PuTTY Ed25519 Signature ecc-ssh.c eddsa_verify weak authentication PuTTY Ed25519 Signature ecc-ssh.c eddsa_verify signature verification

Sun, 22 Mar 2026 12:30:00 +0000

Type Values Removed Values Added
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 弱身份验证. 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.
Title PuTTY Ed25519 Signature ecc-ssh.c eddsa_verify weak authentication
First Time appeared Putty
Putty putty
Weaknesses CWE-345
CWE-347
CPEs cpe:2.3:a:putty:putty:*:*:*:*:*:*:*:*
Vendors & Products Putty
Putty putty
References
Metrics cvssV2_0

{'score': 2.6, 'vector': 'AV:N/AC:H/Au:N/C:N/I:P/A:N/E:POC/RL:OF/RC:C'}

cvssV3_0

{'score': 3.7, 'vector': 'CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N/E:P/RL:O/RC:C'}

cvssV3_1

{'score': 3.7, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N/E:P/RL:O/RC:C'}

cvssV4_0

{'score': 6.3, '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'}

Subscriptions

Putty Putty
cve-icon MITRE

Status: PUBLISHED

Assigner: VulDB

Published:

Updated: 2026-03-23T15:32:42.204Z

Reserved: 2026-03-13T12:09:58.769Z

Link: CVE-2026-4115

cve-icon Vulnrichment

Updated: 2026-03-23T15:32:37.420Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-03-22T13:16:20.377

Modified: 2026-03-23T14:31:37.267

Link: CVE-2026-4115

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-03-25T14:46:30Z

Weaknesses