CVE-2026-41197
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedNoir is a Domain Specific Language for SNARK proving systems that is designed to use any ACIR compatible proving system, and Brillig is the bytecode ACIR uses for non-determinism. Noir programs can invoke external functions through foreign calls. When compiling to Brillig bytecode, the SSA instructions are processed block-by-block in `BrilligBlock::compile_block()`. When the compiler encounters an `Instruction::Call` with a `Value::ForeignFunction` target, it invokes `codegen_call()` in `brillig_call/code_gen_call.rs`, which dispatches to `convert_ssa_foreign_call()`. Before emitting the foreign call opcode, the compiler must pre-allocate memory for any array results the call will return. This happens through `allocate_external_call_results()`, which iterates over the result types. For `Type::Array` results, it delegates to `allocate_foreign_call_result_array()` to recursively allocate memory on the heap for nested arrays. The `BrilligArray` struct is the internal representation of a Noir array in Brillig IR. Its `size` field represents the semi-flattened size, the total number of memory slots the array occupies, accounting for the fact that composite types like tuples consume multiple slots per element. This size is computed by `compute_array_length()` in `brillig_block_variables.rs`. For the outer array, `allocate_external_call_results()` correctly uses `define_variable()`, which internally calls `allocate_value_with_type()`. This function applies the formula above, producing the correct semi-flattened size. However, for nested arrays, `allocate_foreign_call_result_array()` contains a bug. The pattern `Type::Array(_, nested_size)` discards the inner types with `_` and uses only `nested_size`, the semantic length of the nested array (the number of logical elements), not the semi-flattened size. For simple element types this works correctly, but for composite element types it under-allocates. Foreign calls returning nested arrays of tuples or other composite types corrupt the Brillig VM heap. Version 1.0.0-beta.19 fixes this issue.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceThe Noir compiler's Brillig backend incorrectly calculates heap memory allocation for nested arrays returned from foreign function calls. The `allocate_foreign_call_result_array()` function uses the semantic array length instead of the semi-flattened size, causing under-allocation for nested arrays containing composite types like tuples. This results in heap corruption in the Brillig VM when foreign calls return such nested arrays.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- Authentication
- X
- User interaction
- None
- Scope
- X
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Determine Noir compiler versionRun 'noirc --version' or check the version field in your project's package.json or Cargo.toml if using Noir as a dependencyAffected if Version is before 1.0.0-beta.19 (older versions have the flawed allocation logic)
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Identify foreign function usageSearch source code for '#[foreign]' attribute or 'extern "C"' blocks that define foreign functions exposed to Noir programsAffected if Your codebase defines foreign functions that return data to Noir
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Check for nested array returns from foreign callsReview foreign function signatures to see if any return types involve arrays (e.g., Vec<T> in Rust or dynamic arrays in other FFI languages)Affected if Foreign functions return array types to Noir
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Inspect for composite types in returned arraysExamine the element types of arrays returned from foreign calls; look for tuples, structs, or other composite data structures as array elementsAffected if Any foreign function returns an array where the element type is a tuple or composite type
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Verify Brillig VM executionConfirm your Noir program executes Brillig bytecode (enabled by default for programs using foreign functions or certain advanced features); check for crashes or memory errors during FFI operationsAffected if Program uses Brillig VM and exhibits crashes when processing foreign call results containing nested composite arrays
You are affected if running Noir version before 1.0.0-beta.19 AND your code uses foreign functions that return nested arrays containing composite types like tuples, which can cause heap corruption in the Brillig VM.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scopedUpgrade Noir to version 1.0.0-beta.19 or later to obtain the corrected array allocation logic for foreign call results.
1.0.0-beta.19
- Check the current Noir version being used in the project (e.g., via cargo show noir or package.json dependencies)
- Upgrade the Noir compiler to version 1.0.0-beta.19 or later
- Rebuild and test the Noir programs that make foreign calls returning nested arrays of composite types
- Verify that the heap corruption issue is resolved by running the affected programs
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation1.0 h
- Testing4.0 h
- Review / QA2.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2026-41197 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-41197 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
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