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Logic Vulnerability

The class of bug no scanner sees,
because no one told it the rules.

Pattern-based scanners catch taint flows. They miss the bug where a user ID flows to a database without an ownership check. CYBRET mines invariants from your code, your specs, and your real traffic, then generates semantic fuzz harnesses that prove, with a safe replay, that an authenticated user can read somebody else's order.

27
Invariants mined per service
15%
Of critical bugs (industry avg)
0
Signatures
<30s
Invariant to test case
Capabilities

Signatures are over.
Rules are the new primitive.

Invariant mining engine
Reads your controllers, your OpenAPI, and a week of real traffic to extract the rules the system actually enforces: ownership, state machines, temporal constraints, monetary bounds.
Semantic fuzzer
Not byte-level noise. Typed, auth-aware requests that target invariant boundaries, mutated until an invariant breaks or every branch is covered.
Intent-deviation detector
When a handler deviates from the documented intent (spec says owner-only, code checks role-only) we raise a finding with both artifacts cited, and the divergence line.
Multi-step chain solver
Some logic bugs need three requests in a specific order. A symbolic solver plans the chain, checks preconditions, and constructs a reproducible attack without brute force.
Counterfactual test generator
"If this user were in a different tenant, would the same request succeed?" We generate the identity-swapped, tenant-swapped, role-swapped variants automatically.
Proof-of-exploit capsule
Each finding ships with a safe, replayable capsule the engineer can run locally. No vague "potential issue" — the bug either reproduces, or the finding is retracted.
How it works

From your system's rules
to a test that breaks them.

Logic bugs are 15% of critical findings and 0% of most scanners. We close the gap by teaching the scanner what your system is supposed to enforce, and then trying, carefully, to break it.

01
Mine
Invariants extracted from code (ownership guards, state transitions), from spec (OpenAPI, GraphQL schemas, Prisma models), and from traffic (baseline enforcement patterns).
Code + spec + traffic
02
Propose
Each invariant becomes a hypothesis: "only the order owner can refund." A semantic fuzzer plans requests that would falsify it, auth-aware and tenant-aware.
Hypothesis-driven
03
Prove
Safe-mode replay runs the candidate attack against a disposable environment. A violation becomes a capsule: request chain, response, delta, and the invariant it broke.
Production-safe
04
Protect
Confirmed violations ship to the service owner with the spec line, the code line, the invariant, and a suggested guard. Regressions are caught by the same harness in CI.
Regression-proof
Surface

Invariants, violations, and the replay.

Get a guided tour
app.cybret.ai / logic-vuln / billing-svc
27
Invariants mined
3
Broken
1
Drifting
23
Holding
Invariants · billing-svc
order.owner == request.userbroken
Source · code + spec
refund.amount ≤ order.totalholding
Source · code
status: draft → submitted → paidholding
Source · spec
cart.total == Σ(item.price × qty)drifting
Source · traffic
Proof-of-exploit capsuleBOLA · CONFIRMED
00.000s
POST /orders
user=alice → 201 · id=ord_18af
00.214s
GET /orders/ord_18af
user=alice → 200 · owner=alice
00.318s
POST /orders/ord_18af/refund
user=bob → 200 · amount=$249
violation · order.owner == request.user
Spec sheet

The boring details
that determine fit.

For the AppSec lead who has tried fuzzing and got nothing but 500s. We built this for them first.

Invariant sources
Code (controllers, guards) · OpenAPI · GraphQL · Prisma / SQL schema · live traffic
Language coverage
TypeScript · JavaScript · Python · Go · Java · Kotlin · Ruby · C# · Rust
Fuzz harness generation
Auth-aware · tenant-aware · multi-step · symbolic precondition solver
Safety
Production-safe mode · rate-limited · idempotent-only · canary tenants · full audit log
Outputs
Jira · Linear · ServiceNow · Slack · PR comment · replay capsule · CI regression test
Deployment
SaaS · single-tenant · BYO-VPC · air-gapped on Enterprise
Integrations
GitHub · GitLab · Bitbucket · Postman · Burp · k6 · Datadog · Grafana
Data residency
US · EU (Frankfurt) · UK · AU · CA · BYOK on Enterprise
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