In Bitcoin Core before v0.13.0, a non-final alert is able to block the special "final alert" (which is supposed to override all other alerts) because operations occur in the wrong order. This behavior occurs in the remote network alert system (deprecated since Q1 2016). This affects other uses of the codebase, such as Bitcoin Knots before v0.13.0.knots20160814 and many altcoins.

Bitcoin Core before v0.13.0 allows denial of service (memory exhaustion) triggered by the remote network alert system (deprecated since Q1 2016) if an attacker can sign a message with a certain private key that had been known by unintended actors, because of an infinitely sized map. This affects other uses of the codebase, such as Bitcoin Knots before v0.13.0.knots20160814 and many altcoins.

The Bitpie application through 3.2.4 for Android and iOS uses cleartext storage for digital currency initial keys, which allows local users to steal currency by leveraging root access to read /com.biepie/shared_prefs/com.bitpie_preferences.xml (on Android) or a plist file in the app data folder (on iOS).

Cross Site Scripting (XSS) exists in PHP Scripts Mall Bitcoin MLM Software 1.0.2 via a profile field.

Electrum Technologies GmbH Electrum Bitcoin Wallet version prior to version 3.0.5 contains a Missing Authorization vulnerability in JSONRPC interface that can result in Bitcoin theft, if the user's wallet is not password protected. This attack appear to be exploitable via The victim must visit a web page with specially crafted javascript. This vulnerability appears to have been fixed in 3.0.5.

The Bitcoin Proof-of-Work algorithm does not consider a certain attack methodology related to 80-byte block headers with a variety of initial 64-byte chunks followed by the same 16-byte chunk, multiple candidate root values ending with the same 4 bytes, and calculations involving sqrt numbers. This violates the security assumptions of (1) the choice of input, outside of the dedicated nonce area, fed into the Proof-of-Work function should not change its difficulty to evaluate and (2) every Proof-of-Work function execution should be independent. NOTE: a number of persons feel that this methodology is a benign mining optimization, not a vulnerability

In Bitcoin Knots v0.11.0.ljr20150711 through v0.13.0.knots20160814 (fixed in v0.13.1.knots20161027), the debug console stores sensitive information including private keys and the wallet passphrase in its persistent command history.

The Bloom Filter implementation in bitcoind and Bitcoin-Qt 0.8.x before 0.8.4rc1 allows remote attackers to cause a denial of service (divide-by-zero error and daemon crash) via a crafted sequence of messages.

Unspecified vulnerability in bitcoind and Bitcoin-Qt 0.8.x allows remote attackers to cause a denial of service (memory consumption) via a large amount of tx message data.

The HTTPAuthorized function in bitcoinrpc.cpp in bitcoind 0.8.1 provides information about authentication failure upon detecting the first incorrect byte of a password, which makes it easier for remote attackers to determine passwords via a timing side-channel attack.