SRP_user_pwd *SRP_VBASE_get_by_user(SRP_VBASE *vb, char *username)
{
    int i;
    SRP_user_pwd *user;
    unsigned char digv[SHA_DIGEST_LENGTH];
    unsigned char digs[SHA_DIGEST_LENGTH];
    EVP_MD_CTX *ctxt = NULL;

    if (vb == NULL)
        return NULL;
    for (i = 0; i < sk_SRP_user_pwd_num(vb->users_pwd); i++) {
        user = sk_SRP_user_pwd_value(vb->users_pwd, i);
        if (strcmp(user->id, username) == 0)
            return user;
    }
    if ((vb->seed_key == NULL) ||
        (vb->default_g == NULL) || (vb->default_N == NULL))
        return NULL;

/* if the user is unknown we set parameters as well if we have a seed_key */

    if ((user = SRP_user_pwd_new()) == NULL)
        return NULL;

    SRP_user_pwd_set_gN(user, vb->default_g, vb->default_N);

    if (!SRP_user_pwd_set_ids(user, username, NULL))
        goto err;

    if (RAND_bytes(digv, SHA_DIGEST_LENGTH) <= 0)
        goto err;
    ctxt = EVP_MD_CTX_new();
    EVP_DigestInit_ex(ctxt, EVP_sha1(), NULL);
    EVP_DigestUpdate(ctxt, vb->seed_key, strlen(vb->seed_key));
    EVP_DigestUpdate(ctxt, username, strlen(username));
    EVP_DigestFinal_ex(ctxt, digs, NULL);
    EVP_MD_CTX_free(ctxt);
    ctxt = NULL;
    if (SRP_user_pwd_set_sv_BN(user,
                               BN_bin2bn(digs, SHA_DIGEST_LENGTH, NULL),
                               BN_bin2bn(digv, SHA_DIGEST_LENGTH, NULL)))
        return user;

 err:
    EVP_MD_CTX_free(ctxt);
    SRP_user_pwd_free(user);
    return NULL;
}
This vulnerability category highlights issues in resource management where failures to properly release memory, file handles, or other resources can degrade system performance or enable denial-of-service conditions.