Deeper CPI Nesting
October 2026 • Solana Foundation
A cross-program invocation, or CPI, lets one Solana program call another during the same transaction. The called program can make its own CPI, forming a chain. Today that chain stops at 4 calls. After this change it can reach 8.
This benefits composability, such as complex DeFi interactions where a wallet calls an app that calls a router that calls several liquidity programs, and it enables tooling that wraps other programs, such as the offline signing programs replacing durable nonces (see Durable Nonce Deprecation). The limit is runtime-wide and applies to legacy, v0, and v1 transactions alike. A separate change raises the number of accounts a v1 transaction can name; see More Accounts per Transaction.
| Expected Mainnet Activation Date | After Agave 4.4; date to be determined |
| Devnet Activation | Not activated. Already active by default on solana-test-validator, see below |
| Breaking Change? | No |
| Indexing Changes Required? | Yes, for tools that hardcode a stack depth of 5 |
| Feature Gate | 6TkHkRmP7JZy1fdM6fg5uXn76wChQBWGokHBJzrLB3mj |
| Proposal | SIMD-0268 |
Current feature gate activation status:
| Clúster | Estado de activación |
|---|---|
| Testnet | No activada |
| Devnet | No activada |
| Mainnet | No activada |
Test It Locally
The gate has been in Agave since 4.2, and solana-test-validator activates
every known feature gate by default. With Agave CLI 4.2 or later, the 8-call
limit is already live on a local validator:
# All known feature gates, including this one, are active by default
solana-test-validator
# Reproduce mainnet behavior by deactivating the gate
solana-test-validator --deactivate-feature 6TkHkRmP7JZy1fdM6fg5uXn76wChQBWGokHBJzrLB3mj
# Anchor starts the same validator, so `anchor test` runs with the new limit
anchor test
Does This Affect Me?
For UsersNo action needed.+
Nothing changes about how you use wallets or applications. Transactions, fees, and confirmation times stay the same.
For DevelopersNothing breaks onchain. Update dependencies that hardcode the old limit, and check logic that branches on stack height.+
Existing programs keep working. A program that asserts
sol_get_stack_height() == TRANSACTION_LEVEL_STACK_HEIGHT behaves exactly as
before; the change raises the ceiling, not how stack height is reported.
| If you | Breaking? | What you have to do |
|---|---|---|
| Call other programs from your program | No | Nothing. After activation you can nest up to 8 levels deep instead of 4. |
| Wrap other programs, e.g. a smart wallet | No | Nothing. Programs you call gain back the depth your wrapper consumes. |
| Branch on stack height in your program | Check | Logic that treats height 5 as the deepest possible call, or rejects anything above it, needs a second look. |
| Index, decode, or simulate transactions | Yes | Update dependencies. Indexing frameworks and local test tools pin the stack depth; Carbon hardcodes MAX_INSTRUCTION_STACK_DEPTH = 5. |
Most apps will need a dependency update somewhere in their stack, even if their own code never touches the limit. Tools pinned to the old constant may truncate or reject inner instructions nested deeper than 5.
One security note: a deeper chain means more programs sit between the user's signature and the final effect. Wallet simulation should show the full inner-instruction tree, so make sure that view isn't capped at depth 5. Solana's reentrancy rule is unchanged: a program may call itself directly (A → A), but cannot be re-entered through another program (A → B → A). Deeper chains do not relax that; see CPI execution.
For Validator OperatorsNo configuration changes. Run the release as usual.+
The limit lives in the runtime behind a feature gate. There is nothing to configure.
Technical Details
SIMD-0268
raises the maximum number of nested CPI calls from 4 to 8. The top-level
instruction is stack height 1, so the maximum total stack height rises from 5
to 9: eight nested program calls instead of four. When the gate activates,
Agave uses MAX_INSTRUCTION_STACK_DEPTH_SIMD_0268 (9) instead of
MAX_INSTRUCTION_STACK_DEPTH (5).
The SIMD specifies that the gate should only be activated after SIMD-0219, Stricter ABI and Runtime Constraints, which is still under review.
About This Upgrade
Raising the limit to 8 lets protocols stay modular instead of merging layers to fit under it, with no change to how existing transactions execute.
Learn more: Solana Upgrades