diff --git a/CHANGELOG.md b/CHANGELOG.md
index f24241a..cebd6dd 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Security
+- Upgraded `python-jose` from 3.3.0 to 3.5.0 to fix CVE: algorithm confusion vulnerability with OpenSSH ECDSA keys (affected versions < 3.4.0).
+
 ### Added
 - **Unified Google OAuth flow**: Google Sign-In now requests all Gmail API scopes (`gmail.insert`, `gmail.labels`, `gmail.readonly`) in the same consent screen, so users no longer need a separate "Connect Gmail" step after signing in with Google. Gmail credentials are stored automatically on successful sign-in.
 - `include_granted_scopes=true` added to both the login and Gmail authorize URLs so scope additions take effect for users who previously connected.
diff --git a/backend/requirements.txt b/backend/requirements.txt
index 3510b4d..0827c49 100644
--- a/backend/requirements.txt
+++ b/backend/requirements.txt
@@ -11,7 +11,7 @@ psycopg2-binary==2.9.11
 asyncpg==0.31.0
 
 # Authentication
-python-jose[cryptography]==3.3.0
+python-jose[cryptography]==3.5.0  # Updated: Fixed algorithm confusion with OpenSSH ECDSA keys (was 3.3.0)
 bcrypt==4.3.0
 python-multipart==0.0.22  # Updated: Fixed multiple vulnerabilities (was 0.0.6)
 authlib==1.6.9  # Updated: Fixed OIDC hash binding, JWE RSA1_5 padding oracle, alg:none bypass, JWK header injection (was 1.6.6)
diff --git a/docs/TODO.md b/docs/TODO.md
index 7dc86fe..9bc8fbe 100644
--- a/docs/TODO.md
+++ b/docs/TODO.md
@@ -11,6 +11,7 @@ Comprehensive task breakdown for repository improvements and production readines
 - [x] Implement CSRF protection middleware
 - [x] Document all error codes in docs/ERRORS.md
 - [x] Create security ADR (Architecture Decision Records)
+- [x] Upgrade `python-jose` 3.3.0 → 3.5.0 (algorithm confusion with OpenSSH ECDSA keys, CVE, affected < 3.4.0)
 
 ### In Progress 🔨
 - [ ] Enable rate limiting per user/tier