CodeQL documentation

Use of a version of OpenSSL with Heartbleed

ID: cpp/openssl-heartbleed
Kind: problem
Severity: error
Precision: very-high
   - security
   - external/cwe/cwe-327
   - external/cwe/cwe-788
Query suites:
   - cpp-code-scanning.qls
   - cpp-security-extended.qls
   - cpp-security-and-quality.qls

Click to see the query in the CodeQL repository

Earlier versions of the popular OpenSSL library suffer from a buffer overflow in its “heartbeat” code. Because of the location of the problematic code, this vulnerability is often called “Heartbleed”.

Software that includes a copy of OpenSSL should be sure to use a current version of the library. If it uses an older version, it will be vulnerable to any network site it connects with.


Upgrade to the latest version of OpenSSL. This problem was fixed in version 1.0.1g.


The following code is present in earlier versions of OpenSSL. The payload variable is the number of bytes that should be copied from the request back into the response. The call to memcpy does this copy. The problem is that payload is supplied as part of the remote request, and there is no code that checks the size of it. If the caller supplies a very large value, then the memcpy call will copy memory that is outside the request packet.

tls1_process_heartbeat(SSL *s)
    unsigned char *p = &s->s3->[0], *pl;
    unsigned short hbtype;
    unsigned int payload;
    /* ... */
    hbtype = *p++;
    n2s(p, payload);
    pl = p;
    /* ... */
    if (hbtype == TLS1_HB_REQUEST)
            /* ... */
            memcpy(bp, pl, payload);  // BAD: overflow here
            /* ... */
    /* ... */