Glossary OS

Plain meaning

Start with the shortest useful explanation before going deeper.

A vulnerability arising from the use of ctx.remaining_accounts in Anchor (or unchecked trailing accounts in native programs), where accounts passed beyond the explicitly declared account struct are not subject to any automatic owner, signer, or constraint checks, leaving it entirely to the program to validate them. Attackers can exploit this by injecting unexpected accounts — fake mints, unauthorized signers, or accounts owned by a malicious program — that the program then treats as trusted inputs. Programs using remaining_accounts must manually verify every account's key, owner, is_signer, and is_writable properties before use, making this pattern a frequent audit finding.

Mental model

Use the quick analogy first so the term is easier to reason about when you meet it in code, docs, or prompts.

Think of it as a building block that connects one definition to the larger Solana system around it.

Technical context

Place the term inside its Solana layer so the definition is easier to reason about.

Failure modes, audits, attack surfaces, and safe design patterns.

Why builders care

Turn the term from vocabulary into something operational for product and engineering work.

This term unlocks adjacent concepts quickly, so it works best when you treat it as a junction instead of an isolated definition.

AI handoff

Use this compact block when you want to give an agent or assistant grounded context without dumping the entire page.

Remaining Accounts Misuse (remaining-accounts)
Category: Security
Definition: A vulnerability arising from the use of ctx.remaining_accounts in Anchor (or unchecked trailing accounts in native programs), where accounts passed beyond the explicitly declared account struct are not subject to any automatic owner, signer, or constraint checks, leaving it entirely to the program to validate them. Attackers can exploit this by injecting unexpected accounts — fake mints, unauthorized signers, or accounts owned by a malicious program — that the program then treats as trusted inputs. Programs using remaining_accounts must manually verify every account's key, owner, is_signer, and is_writable properties before use, making this pattern a frequent audit finding.
Related: Instruction, Account

Glossary Copilot

Ask grounded Solana questions without leaving the glossary.

Use glossary context, relationships, mental models, and builder paths to get structured answers instead of generic chat output.

Open full Copilot workspace

Question

Explain this code

Optional: paste Anchor, Solana, or Rust code so the Copilot can map primitives back to glossary terms.

Ask a glossary-grounded question

The Copilot will answer using the current term, related concepts, mental models, and the surrounding glossary graph.

Concept graph

See the term as part of a network, not a dead-end definition.

These branches show which concepts this term touches directly and what sits one layer beyond them.

Branch

Instruction

A single operation within a transaction that invokes a program. An instruction specifies: (1) the program ID to call, (2) an array of account metas (pubkey, is_signer, is_writable), and (3) an opaque data byte array. Programs decode the instruction data to determine which operation to perform.

Transaction Program

Open term

Branch

Account

The fundamental data storage unit on Solana. Every piece of state is stored in an account identified by a 32-byte public key. Accounts hold a lamport balance, an owner program, a data byte array (up to 10MB), and an executable flag. Only the owning program can modify an account's data, but anyone can credit lamports to it.

Public Key (Pubkey)Lamport

Open term

Next concepts to explore

Keep the learning chain moving instead of stopping at one definition.

These are the next concepts worth opening if you want this term to make more sense inside a real Solana workflow.

Programming Model

Instruction

A single operation within a transaction that invokes a program. An instruction specifies: (1) the program ID to call, (2) an array of account metas (pubkey, is_signer, is_writable), and (3) an opaque data byte array. Programs decode the instruction data to determine which operation to perform.

Open term

Programming Model

Account

The fundamental data storage unit on Solana. Every piece of state is stored in an account identified by a 32-byte public key. Accounts hold a lamport balance, an owner program, a data byte array (up to 10MB), and an executable flag. Only the owning program can modify an account's data, but anyone can credit lamports to it.

Open term

Security

Rent Evasion

Attack technique where a malicious actor attempts to circumvent Solana's rent mechanism by manipulating account lamport balances to avoid rent-exemption thresholds, or by exploiting programs that don't properly enforce minimum balance requirements when withdrawing lamports from accounts.

Open term

Security

Reinitialization Attack

A vulnerability where a program allows an already-initialized account to be initialized a second time, overwriting its state — including authority or ownership fields — with attacker-supplied data, effectively letting the attacker seize control of an existing account without going through normal privilege checks. The canonical defense is storing an is_initialized boolean or an Anchor discriminator in the account and asserting it is false (or that the discriminator is unset) at the start of every initialization instruction; Anchor's init constraint enforces this by failing if the account's discriminator is already non-zero.

Open term

Commonly confused with

Terms nearby in vocabulary, acronym, or conceptual neighborhood.

These entries are easy to mix up when you are reading quickly, prompting an LLM, or onboarding into a new layer of Solana.

Securityclosing-accounts

Closing Accounts Vulnerability

A vulnerability that arises when a program closes an account by zeroing its data and transferring lamports without setting the account's discriminator or data to a sentinel closed state before the end of the instruction, leaving a window within the same transaction where other instructions can still interact with the now-empty account. The Solana runtime only removes an account from the account set when its lamports reach zero at the end of a transaction, so mid-transaction the account still exists and a subsequent instruction can re-fund it and reinstate stale data, enabling an account revival attack. Anchor's close constraint writes a CLOSED_ACCOUNT_DISCRIMINATOR (8 bytes of 0xff) and uses a force-defund mechanism to prevent resurrection.

Open term

Securityduplicate-mutable-accounts

Duplicate Mutable Accounts

A vulnerability where the same account is passed twice in the accounts list for a single instruction under different argument names, and the program writes to what it believes are two independent accounts, with the second write silently overwriting the first on the single underlying account in the runtime's account map. For example, if from and to in a transfer handler reference the same key, debiting from and crediting to nets out to a free credit. In native programs the check requires comparing account keys; Anchor automatically detects duplicate mutable accounts and returns an error when the same pubkey appears more than once in writable positions within a single instruction's account list.

Open term

Related terms

Follow the concepts that give this term its actual context.

Glossary entries become useful when they are connected. These links are the shortest path to adjacent ideas.

Programming Modelinstruction

Instruction

A single operation within a transaction that invokes a program. An instruction specifies: (1) the program ID to call, (2) an array of account metas (pubkey, is_signer, is_writable), and (3) an opaque data byte array. Programs decode the instruction data to determine which operation to perform.

Open term

Programming Modelaccount

Account

The fundamental data storage unit on Solana. Every piece of state is stored in an account identified by a 32-byte public key. Accounts hold a lamport balance, an owner program, a data byte array (up to 10MB), and an executable flag. Only the owning program can modify an account's data, but anyone can credit lamports to it.

Open term

Stay in the same layer and keep building context.

These entries live beside the current term and help the page feel like part of a larger knowledge graph instead of a dead end.

Security

Missing Signer Check

A vulnerability where a program accepts an account in a privileged role (e.g., admin, authority, payer) without verifying that the account actually signed the transaction, allowing any caller to impersonate that authority by simply passing the target pubkey as an instruction account. In native Solana programs, the check requires asserting account.is_signer == true; in Anchor, the Signer<'info> type enforces this automatically. Exploitation lets an attacker bypass all access control gated on authority equality checks, making it one of the most critical and commonly audited vulnerabilities in Solana programs.

Open term

Security

Missing Owner Check

A vulnerability where a program deserializes and trusts account data without first confirming that the account is owned by the expected program, allowing an attacker to substitute a maliciously crafted account owned by a different program whose byte layout happens to satisfy the deserialization. On Solana, every account stores a 32-byte owner field set to the program that created it; native programs must assert account.owner == &expected_program_id, while Anchor's Account<'info, T> wrapper performs this check automatically. Failure to validate ownership can lead to complete auth bypass if an attacker can construct a fake account whose data parses into a struct with elevated privileges.

Open term

Security

Arbitrary CPI

A vulnerability where a program accepts an arbitrary program account from the caller and invokes it via Cross-Program Invocation (CPI) without verifying it matches a known, trusted program ID, effectively letting an attacker substitute a malicious program that executes under the victim program's authority or manipulates accounts the victim program passes to it. A common pattern is accepting a token_program account without checking it equals spl_token::ID, so the attacker passes a lookalike program that records or drains account data. Prevention requires hard-coding or explicitly checking the program ID before every CPI call.

Open term

Security

PDA Substitution Attack

A vulnerability where a program derives a PDA internally but accepts an externally supplied account as that PDA without re-deriving and comparing the address, allowing an attacker to pass a different PDA (derived from attacker-controlled seeds) that the program will treat as legitimate. Because PDAs are deterministic, the only way to guarantee account identity is to call Pubkey::find_program_address (or equivalent) with the expected seeds inside the program and assert the result equals the supplied key. Anchor's seeds and bump constraints on the Account type automate this re-derivation and equality check.

Open term