Vulnerability in PuTTY (CVE-2026-4115)
Summary
Vulnerability in PuTTY (CVE-2026-4115). Risk of unauthorized operations or information disclosure.
Original description
The description as published by the source.
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.
Source: NIST National Vulnerability Database NVD
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-4115 has been found in PuTTY.
Risk of unauthorized operations or information disclosure. CVSS score: 3.7/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "PuTTY CVE-2026-4115" on the vendor's site.
CVE-2026-4115 (PuTTY) — CWE-345 / CVSS v3 3.7
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-345) exists in PuTTY.
Check the vendor advisory for the affected versions of PuTTY.
Severity: Low (CVSS 3.7/10). Risk of unauthorized operations or information disclosure.
Update to the patched release per vendor advisory.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'PuTTY' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'PuTTY' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
PuTTYを grep し、稼働しているサービス・バージョンを把握する。 -
2Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2026-4115 putty
- Ubuntu UBUNTU-CVE-2026-4115 putty
References
- advisory cna@vuldb.com
- advisory cna@vuldb.com
- advisory cna@vuldb.com
- advisory cna@vuldb.com
- exploit cna@vuldb.com
- web cna@vuldb.com
- web cna@vuldb.com
- web cna@vuldb.com